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Tetrahedron

Index Tetrahedron

In geometry, a tetrahedron (tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertices. [1]

Table of Contents

  1. 223 relations: Aerodrome, Aerodynamics, Allotropes of phosphorus, Alternating group, Alternation (geometry), Ammonium, Angular defect, Antiprism, Apex (geometry), Approximation, Aristotle, Arithmetic mean, Artificial intelligence, Base (geometry), Bisection, Boerdijk–Coxeter helix, Caltrop, Cambridge University Press, Cartesian coordinate system, Cayley–Menger determinant, Central angle, Centroid, Cevian, Chemical engineering, Chirality, Circumscribed sphere, Civil engineering, Commandino's theorem, Compound of five tetrahedra, Compound of ten tetrahedra, Computational fluid dynamics, Concurrent lines, Conformal map, Conjugacy class, Convex hull, Convex polytope, Convex set, Covalent bond, Coxeter element, Coxeter group, Coxeter notation, Coxeter–Dynkin diagram, Crux Mathematicorum, Crystal, Császár polyhedron, Cube, Cyclic group, Degrees of freedom (statistics), Deltahedron, Demihypercube, ... Expand index (173 more) »

  2. Deltahedra
  3. Platonic solids
  4. Prismatoid polyhedra
  5. Pyramids (geometry)
  6. Self-dual polyhedra
  7. Tetrahedra

Aerodrome

An aerodrome is a location from which aircraft flight operations take place, regardless of whether they involve air cargo, passengers, or neither, and regardless of whether it is for public or private use.

See Tetrahedron and Aerodrome

Aerodynamics

Aerodynamics (ἀήρ aero (air) + δυναμική (dynamics)) is the study of the motion of air, particularly when affected by a solid object, such as an airplane wing.

See Tetrahedron and Aerodynamics

Allotropes of phosphorus

Elemental phosphorus can exist in several allotropes, the most common of which are white and red solids.

See Tetrahedron and Allotropes of phosphorus

Alternating group

In mathematics, an alternating group is the group of even permutations of a finite set.

See Tetrahedron and Alternating group

Alternation (geometry)

In geometry, an alternation or partial truncation, is an operation on a polygon, polyhedron, tiling, or higher dimensional polytope that removes alternate vertices.

See Tetrahedron and Alternation (geometry)

Ammonium

Ammonium is a modified form of ammonia that has an extra hydrogen atom.

See Tetrahedron and Ammonium

Angular defect

In geometry, the (angular) defect (or deficit or deficiency) means the failure of some angles to add up to the expected amount of 360° or 180°, when such angles in the Euclidean plane would.

See Tetrahedron and Angular defect

Antiprism

In geometry, an antiprism or is a polyhedron composed of two parallel direct copies (not mirror images) of an polygon, connected by an alternating band of triangles. Tetrahedron and antiprism are Prismatoid polyhedra.

See Tetrahedron and Antiprism

Apex (geometry)

In geometry, an apex (apices) is the vertex which is in some sense the "highest" of the figure to which it belongs.

See Tetrahedron and Apex (geometry)

Approximation

An approximation is anything that is intentionally similar but not exactly equal to something else.

See Tetrahedron and Approximation

Aristotle

Aristotle (Ἀριστοτέλης Aristotélēs; 384–322 BC) was an Ancient Greek philosopher and polymath.

See Tetrahedron and Aristotle

Arithmetic mean

In mathematics and statistics, the arithmetic mean, arithmetic average, or just the mean or average (when the context is clear) is the sum of a collection of numbers divided by the count of numbers in the collection.

See Tetrahedron and Arithmetic mean

Artificial intelligence

Artificial intelligence (AI), in its broadest sense, is intelligence exhibited by machines, particularly computer systems.

See Tetrahedron and Artificial intelligence

Base (geometry)

In geometry, a base is a side of a polygon or a face of a polyhedron, particularly one oriented perpendicular to the direction in which height is measured, or on what is considered to be the "bottom" of the figure.

See Tetrahedron and Base (geometry)

Bisection

In geometry, bisection is the division of something into two equal or congruent parts (having the same shape and size).

See Tetrahedron and Bisection

Boerdijk–Coxeter helix

The Boerdijk–Coxeter helix, named after H. S. M. Coxeter and, is a linear stacking of regular tetrahedra, arranged so that the edges of the complex that belong to only one tetrahedron form three intertwined helices.

See Tetrahedron and Boerdijk–Coxeter helix

Caltrop

A caltrop (also known as caltrap, galtrop, cheval trap, galthrap, galtrap, calthrop, jackrock or crow's footBattle of Alesia (Caesar's conquest of Gaul in 52 BC), Battlefield Detectives program, (2006), rebroadcast: 2008-09-08 on History Channel International (13:00-14:00 hrs EDST); Note: No mention of name caltrop at all, but illustrated and given as battle key to defend Roman lines of circumvallation per recent digs evidence.) is an area denial weapon made up of usually four, but possibly more, sharp nails or spines arranged in such a manner that one of them always points upward from a stable base (for example, a tetrahedron). Tetrahedron and caltrop are tetrahedra.

See Tetrahedron and Caltrop

Cambridge University Press

Cambridge University Press is the university press of the University of Cambridge.

See Tetrahedron and Cambridge University Press

Cartesian coordinate system

In geometry, a Cartesian coordinate system in a plane is a coordinate system that specifies each point uniquely by a pair of real numbers called coordinates, which are the signed distances to the point from two fixed perpendicular oriented lines, called coordinate lines, coordinate axes or just axes (plural of axis) of the system.

See Tetrahedron and Cartesian coordinate system

Cayley–Menger determinant

In linear algebra, geometry, and trigonometry, the Cayley–Menger determinant is a formula for the content, i.e. the higher-dimensional volume, of a n-dimensional simplex in terms of the squares of all of the distances between pairs of its vertices.

See Tetrahedron and Cayley–Menger determinant

Central angle

A central angle is an angle whose apex (vertex) is the center O of a circle and whose legs (sides) are radii intersecting the circle in two distinct points A and B. Central angles are subtended by an arc between those two points, and the arc length is the central angle of a circle of radius one (measured in radians).

See Tetrahedron and Central angle

Centroid

In mathematics and physics, the centroid, also known as geometric center or center of figure, of a plane figure or solid figure is the arithmetic mean position of all the points in the surface of the figure.

See Tetrahedron and Centroid

Cevian

In geometry, a cevian is a line segment which joins a vertex of a triangle to a point on the opposite side of the triangle.

See Tetrahedron and Cevian

Chemical engineering

Chemical engineering is an engineering field which deals with the study of operation and design of chemical plants as well as methods of improving production.

See Tetrahedron and Chemical engineering

Chirality

Chirality is a property of asymmetry important in several branches of science.

See Tetrahedron and Chirality

Circumscribed sphere

In geometry, a circumscribed sphere of a polyhedron is a sphere that contains the polyhedron and touches each of the polyhedron's vertices.

See Tetrahedron and Circumscribed sphere

Civil engineering

Civil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including public works such as roads, bridges, canals, dams, airports, sewage systems, pipelines, structural components of buildings, and railways.

See Tetrahedron and Civil engineering

Commandino's theorem

Commandino's theorem, named after Federico Commandino (1509–1575), states that the four medians of a tetrahedron are concurrent at a point S, which divides them in a 3:1 ratio. Tetrahedron and Commandino's theorem are tetrahedra.

See Tetrahedron and Commandino's theorem

Compound of five tetrahedra

The compound of five tetrahedra is one of the five regular polyhedral compounds.

See Tetrahedron and Compound of five tetrahedra

Compound of ten tetrahedra

The compound of ten tetrahedra is one of the five regular polyhedral compounds.

See Tetrahedron and Compound of ten tetrahedra

Computational fluid dynamics

Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to analyze and solve problems that involve fluid flows.

See Tetrahedron and Computational fluid dynamics

Concurrent lines

In geometry, lines in a plane or higher-dimensional space are concurrent if they intersect at a single point.

See Tetrahedron and Concurrent lines

Conformal map

In mathematics, a conformal map is a function that locally preserves angles, but not necessarily lengths.

See Tetrahedron and Conformal map

Conjugacy class

In mathematics, especially group theory, two elements a and b of a group are conjugate if there is an element g in the group such that b.

See Tetrahedron and Conjugacy class

Convex hull

In geometry, the convex hull, convex envelope or convex closure of a shape is the smallest convex set that contains it.

See Tetrahedron and Convex hull

Convex polytope

A convex polytope is a special case of a polytope, having the additional property that it is also a convex set contained in the n-dimensional Euclidean space \mathbb^n.

See Tetrahedron and Convex polytope

Convex set

In geometry, a subset of a Euclidean space, or more generally an affine space over the reals, is convex if, given any two points in the subset, the subset contains the whole line segment that joins them.

See Tetrahedron and Convex set

Covalent bond

A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms.

See Tetrahedron and Covalent bond

Coxeter element

In mathematics, a Coxeter element is an element of an irreducible Coxeter group which is a product of all simple reflections.

See Tetrahedron and Coxeter element

Coxeter group

In mathematics, a Coxeter group, named after H. S. M. Coxeter, is an abstract group that admits a formal description in terms of reflections (or kaleidoscopic mirrors).

See Tetrahedron and Coxeter group

Coxeter notation

In geometry, Coxeter notation (also Coxeter symbol) is a system of classifying symmetry groups, describing the angles between fundamental reflections of a Coxeter group in a bracketed notation expressing the structure of a Coxeter-Dynkin diagram, with modifiers to indicate certain subgroups.

See Tetrahedron and Coxeter notation

Coxeter–Dynkin diagram

In geometry, a Coxeter–Dynkin diagram (or Coxeter diagram, Coxeter graph) is a graph with numerically labeled edges (called branches) representing a Coxeter group or sometimes a uniform polytope or uniform tiling constructed from the group.

See Tetrahedron and Coxeter–Dynkin diagram

Crux Mathematicorum

Crux Mathematicorum is a scientific journal of mathematics published by the Canadian Mathematical Society.

See Tetrahedron and Crux Mathematicorum

Crystal

A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions.

See Tetrahedron and Crystal

Császár polyhedron

In geometry, the Császár polyhedron is a nonconvex toroidal polyhedron with 14 triangular faces.

See Tetrahedron and Császár polyhedron

Cube

In geometry, a cube is a three-dimensional solid object bounded by six square faces. Tetrahedron and cube are platonic solids and Prismatoid polyhedra.

See Tetrahedron and Cube

Cyclic group

In abstract algebra, a cyclic group or monogenous group is a group, denoted Cn (also frequently \Zn or Zn, not to be confused with the commutative ring of p-adic numbers), that is generated by a single element.

See Tetrahedron and Cyclic group

Degrees of freedom (statistics)

In statistics, the number of degrees of freedom is the number of values in the final calculation of a statistic that are free to vary.

See Tetrahedron and Degrees of freedom (statistics)

Deltahedron

In geometry, a deltahedron (plural deltahedra) is a polyhedron whose faces are all (congruent) equilateral triangles. Tetrahedron and deltahedron are deltahedra.

See Tetrahedron and Deltahedron

Demihypercube

In geometry, demihypercubes (also called n-demicubes, n-hemicubes, and half measure polytopes) are a class of n-polytopes constructed from alternation of an n-hypercube, labeled as hγn for being half of the hypercube family, γn.

See Tetrahedron and Demihypercube

Determinant

In mathematics, the determinant is a scalar-valued function of the entries of a square matrix.

See Tetrahedron and Determinant

Dice

Dice (die or dice) are small, throwable objects with marked sides that can rest in multiple positions.

See Tetrahedron and Dice

Digon

In geometry, a bigon, digon, or a 2-gon, is a polygon with two sides (edges) and two vertices.

See Tetrahedron and Digon

Dihedral angle

A dihedral angle is the angle between two intersecting planes or half-planes.

See Tetrahedron and Dihedral angle

Disphenoid

In geometry, a disphenoid is a tetrahedron whose four faces are congruent acute-angled triangles. Tetrahedron and disphenoid are tetrahedra.

See Tetrahedron and Disphenoid

Dissection into orthoschemes

In geometry, it is an unsolved conjecture of Hugo Hadwiger that every simplex can be dissected into orthoschemes, using a number of orthoschemes bounded by a function of the dimension of the simplex.

See Tetrahedron and Dissection into orthoschemes

Distance-regular graph

In the mathematical field of graph theory, a distance-regular graph is a regular graph such that for any two vertices and, the number of vertices at distance from and at distance from depends only upon,, and the distance between and.

See Tetrahedron and Distance-regular graph

Distance-transitive graph

In the mathematical field of graph theory, a distance-transitive graph is a graph such that, given any two vertices and at any distance, and any other two vertices and at the same distance, there is an automorphism of the graph that carries to and to.

See Tetrahedron and Distance-transitive graph

Dodecahedron

In geometry, a dodecahedron or duodecahedron is any polyhedron with twelve flat faces. Tetrahedron and dodecahedron are individual graphs and platonic solids.

See Tetrahedron and Dodecahedron

Dover Publications

Dover Publications, also known as Dover Books, is an American book publisher founded in 1941 by Hayward and Blanche Cirker.

See Tetrahedron and Dover Publications

Dual polyhedron

In geometry, every polyhedron is associated with a second dual structure, where the vertices of one correspond to the faces of the other, and the edges between pairs of vertices of one correspond to the edges between pairs of faces of the other. Tetrahedron and dual polyhedron are self-dual polyhedra.

See Tetrahedron and Dual polyhedron

Edge (geometry)

In geometry, an edge is a particular type of line segment joining two vertices in a polygon, polyhedron, or higher-dimensional polytope.

See Tetrahedron and Edge (geometry)

Electromagnetic field

An electromagnetic field (also EM field) is a physical field, mathematical functions of position and time, representing the influences on and due to electric charges.

See Tetrahedron and Electromagnetic field

Electromagnetism

In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields.

See Tetrahedron and Electromagnetism

Elliptic geometry

Elliptic geometry is an example of a geometry in which Euclid's parallel postulate does not hold.

See Tetrahedron and Elliptic geometry

Equilateral triangle

In geometry, an equilateral triangle is a triangle in which all three sides have the same length.

See Tetrahedron and Equilateral triangle

Euclidean geometry

Euclidean geometry is a mathematical system attributed to ancient Greek mathematician Euclid, which he described in his textbook on geometry, Elements.

See Tetrahedron and Euclidean geometry

Euler line

In geometry, the Euler line, named after Leonhard Euler, is a line determined from any triangle that is not equilateral.

See Tetrahedron and Euler line

Face (geometry)

In solid geometry, a face is a flat surface (a planar region) that forms part of the boundary of a solid object; a three-dimensional solid bounded exclusively by faces is a polyhedron.

See Tetrahedron and Face (geometry)

Finite element method

The finite element method (FEM) is a popular method for numerically solving differential equations arising in engineering and mathematical modeling.

See Tetrahedron and Finite element method

Fire (classical element)

Fire is one of the four classical elements along with earth, water and air in ancient Greek philosophy and science.

See Tetrahedron and Fire (classical element)

Forum Geometricorum

Forum Geometricorum: A Journal on Classical Euclidean Geometry is a peer-reviewed open-access academic journal that specializes in mathematical research papers on Euclidean geometry.

See Tetrahedron and Forum Geometricorum

Four-dimensional space

Four-dimensional space (4D) is the mathematical extension of the concept of three-dimensional space (3D).

See Tetrahedron and Four-dimensional space

Four-sided die

Four-sided dice, abbreviated d4, are often used in tabletop role-playing games to obtain random integers in the range 1–4. Tetrahedron and Four-sided die are tetrahedra.

See Tetrahedron and Four-sided die

Fundamental domain

Given a topological space and a group acting on it, the images of a single point under the group action form an orbit of the action.

See Tetrahedron and Fundamental domain

Gaspard Monge

Gaspard Monge, Comte de Péluse (9 May 1746 – 28 July 1818) was a French mathematician, commonly presented as the inventor of descriptive geometry, (the mathematical basis of) technical drawing, and the father of differential geometry.

See Tetrahedron and Gaspard Monge

Geometric median

In geometry, the geometric median of a discrete set of sample points in a Euclidean space is the point minimizing the sum of distances to the sample points.

See Tetrahedron and Geometric median

Geometry

Geometry is a branch of mathematics concerned with properties of space such as the distance, shape, size, and relative position of figures.

See Tetrahedron and Geometry

Golden ratio

In mathematics, two quantities are in the golden ratio if their ratio is the same as the ratio of their sum to the larger of the two quantities.

See Tetrahedron and Golden ratio

Goursat tetrahedron

In geometry, a Goursat tetrahedron is a tetrahedral fundamental domain of a Wythoff construction. Tetrahedron and Goursat tetrahedron are tetrahedra.

See Tetrahedron and Goursat tetrahedron

Graph (discrete mathematics)

In discrete mathematics, particularly in graph theory, a graph is a structure consisting of a set of objects where some pairs of the objects are in some sense "related".

See Tetrahedron and Graph (discrete mathematics)

HAL 9000

HAL 9000 (or simply HAL or Hal) is a fictional artificial intelligence character and the main antagonist in Arthur C. Clarke's Space Odyssey series.

See Tetrahedron and HAL 9000

Hamiltonian path

In the mathematical field of graph theory, a Hamiltonian path (or traceable path) is a path in an undirected or directed graph that visits each vertex exactly once.

See Tetrahedron and Hamiltonian path

Handedness

In human biology, handedness is an individual's preferential use of one hand, known as the dominant hand, due to it being stronger, faster or more dextrous.

See Tetrahedron and Handedness

Heron's formula

In geometry, Heron's formula (or Hero's formula) gives the area of a triangle in terms of the three side lengths Letting be the semiperimeter of the triangle, s.

See Tetrahedron and Heron's formula

Heronian tetrahedron

A Heronian tetrahedron (also called a Heron tetrahedron or perfect pyramid) is a tetrahedron whose edge lengths, face areas and volume are all integers. Tetrahedron and Heronian tetrahedron are tetrahedra.

See Tetrahedron and Heronian tetrahedron

Hilbert's third problem

The third of Hilbert's list of mathematical problems, presented in 1900, was the first to be solved.

See Tetrahedron and Hilbert's third problem

Hill tetrahedron

In geometry, the Hill tetrahedra are a family of space-filling tetrahedra. Tetrahedron and Hill tetrahedron are tetrahedra.

See Tetrahedron and Hill tetrahedron

Honeycomb (geometry)

In geometry, a honeycomb is a space filling or close packing of polyhedral or higher-dimensional cells, so that there are no gaps.

See Tetrahedron and Honeycomb (geometry)

Hosohedron

In spherical geometry, an n-gonal hosohedron is a tessellation of lunes on a spherical surface, such that each lune shares the same two polar opposite vertices.

See Tetrahedron and Hosohedron

Hyperbolic space

In mathematics, hyperbolic space of dimension n is the unique simply connected, n-dimensional Riemannian manifold of constant sectional curvature equal to −1.

See Tetrahedron and Hyperbolic space

Incircle and excircles

In geometry, the incircle or inscribed circle of a triangle is the largest circle that can be contained in the triangle; it touches (is tangent to) the three sides.

See Tetrahedron and Incircle and excircles

Inscribed sphere

In geometry, the inscribed sphere or insphere of a convex polyhedron is a sphere that is contained within the polyhedron and tangent to each of the polyhedron's faces.

See Tetrahedron and Inscribed sphere

Isomorphism

In mathematics, an isomorphism is a structure-preserving mapping between two structures of the same type that can be reversed by an inverse mapping.

See Tetrahedron and Isomorphism

Isosceles triangle

In geometry, an isosceles triangle is a triangle that has two sides of equal length.

See Tetrahedron and Isosceles triangle

Johannes Kepler

Johannes Kepler (27 December 1571 – 15 November 1630) was a German astronomer, mathematician, astrologer, natural philosopher and writer on music.

See Tetrahedron and Johannes Kepler

K-vertex-connected graph

In graph theory, a connected graph is said to be -vertex-connected (or -connected) if it has more than vertices and remains connected whenever fewer than vertices are removed.

See Tetrahedron and K-vertex-connected graph

Kaleidocycle

A kaleidocycle or flextangle is a flexible polyhedron connecting six tetrahedra (or disphenoids) on opposite edges into a cycle.

See Tetrahedron and Kaleidocycle

Kaleidoscope

A kaleidoscope is an optical instrument with two or more reflecting surfaces (or mirrors) tilted to each other at an angle, so that one or more (parts of) objects on one end of these mirrors are shown as a regular symmetrical pattern when viewed from the other end, due to repeated reflection.

See Tetrahedron and Kaleidoscope

Klein four-group

In mathematics, the Klein four-group is an abelian group with four elements, in which each element is self-inverse (composing it with itself produces the identity) and in which composing any two of the three non-identity elements produces the third one.

See Tetrahedron and Klein four-group

Law of cosines

In trigonometry, the law of cosines (also known as the cosine formula or cosine rule) relates the lengths of the sides of a triangle to the cosine of one of its angles.

See Tetrahedron and Law of cosines

Law of sines

In trigonometry, the law of sines, sine law, sine formula, or sine rule is an equation relating the lengths of the sides of any triangle to the sines of its angles.

See Tetrahedron and Law of sines

List of spherical symmetry groups

Finite spherical symmetry groups are also called point groups in three dimensions.

See Tetrahedron and List of spherical symmetry groups

Lone pair

In chemistry, a lone pair refers to a pair of valence electrons that are not shared with another atom in a covalent bondIUPAC Gold Book definition: and is sometimes called an unshared pair or non-bonding pair.

See Tetrahedron and Lone pair

Lorenz Leonard Lindelöf

Lorenz Leonard Lindelöf (13 November 1827, Karvia, Finland – 3 March 1908, Helsinki) was a Finnish mathematician and astronomer.

See Tetrahedron and Lorenz Leonard Lindelöf

Marvin Minsky

Marvin Lee Minsky (August 9, 1927 – January 24, 2016) was an American cognitive and computer scientist concerned largely with research of artificial intelligence (AI).

See Tetrahedron and Marvin Minsky

Mathematical Association of America

The Mathematical Association of America (MAA) is a professional society that focuses on mathematics accessible at the undergraduate level.

See Tetrahedron and Mathematical Association of America

Mathematics Magazine

Mathematics Magazine is a refereed bimonthly publication of the Mathematical Association of America.

See Tetrahedron and Mathematics Magazine

Möbius configuration

In geometry, the Möbius configuration or Möbius tetrads is a certain configuration in Euclidean space or projective space, consisting of two tetrahedra that are mutually inscribed: each vertex of one tetrahedron lies on a face plane of the other tetrahedron and vice versa.

See Tetrahedron and Möbius configuration

Median (geometry)

In geometry, a median of a triangle is a line segment joining a vertex to the midpoint of the opposite side, thus bisecting that side.

See Tetrahedron and Median (geometry)

Methane

Methane is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms).

See Tetrahedron and Methane

Midsphere

In geometry, the midsphere or intersphere of a convex polyhedron is a sphere which is tangent to every edge of the polyhedron.

See Tetrahedron and Midsphere

Mirror image

A mirror image (in a plane mirror) is a reflected duplication of an object that appears almost identical, but is reversed in the direction perpendicular to the mirror surface.

See Tetrahedron and Mirror image

Monolith (Space Odyssey)

In Arthur C. Clarke's Space Odyssey series, Monoliths are machines in black cuboids whose sides extend in the precise ratio of 1: 4: 9 (12: 22: 32) built by an unseen extraterrestrial species whom Clarke dubbed the Firstborn and who he suggests are the earliest highly intelligent species to evolve in the Milky Way.

See Tetrahedron and Monolith (Space Odyssey)

Murakami–Yano formula

In geometry, the Murakami–Yano formula, introduced by, is a formula for the volume of a hyperbolic or spherical tetrahedron given in terms of its dihedral angles.

See Tetrahedron and Murakami–Yano formula

N-skeleton

In mathematics, particularly in algebraic topology, the of a topological space presented as a simplicial complex (resp. CW complex) refers to the subspace that is the union of the simplices of (resp. cells of) of dimensions In other words, given an inductive definition of a complex, the is obtained by stopping at the.

See Tetrahedron and N-skeleton

Naval architecture, or naval engineering, is an engineering discipline incorporating elements of mechanical, electrical, electronic, software and safety engineering as applied to the engineering design process, shipbuilding, maintenance, and operation of marine vessels and structures.

See Tetrahedron and Naval architecture

Net (polyhedron)

In geometry, a net of a polyhedron is an arrangement of non-overlapping edge-joined polygons in the plane which can be folded (along edges) to become the faces of the polyhedron.

See Tetrahedron and Net (polyhedron)

Nicolo Tartaglia

Nicolo, known as Tartaglia (1499/1500 – 13 December 1557), was an Italian mathematician, engineer (designing fortifications), a surveyor (of topography, seeking the best means of defense or offense) and a bookkeeper from the then Republic of Venice.

See Tetrahedron and Nicolo Tartaglia

Nine-point circle

In geometry, the nine-point circle is a circle that can be constructed for any given triangle.

See Tetrahedron and Nine-point circle

Numerical analysis

Numerical analysis is the study of algorithms that use numerical approximation (as opposed to symbolic manipulations) for the problems of mathematical analysis (as distinguished from discrete mathematics).

See Tetrahedron and Numerical analysis

Octahedron

In geometry, an octahedron (octahedra or octahedrons) is a polyhedron with eight faces. Tetrahedron and octahedron are deltahedra, individual graphs, platonic solids and Prismatoid polyhedra.

See Tetrahedron and Octahedron

Orbifold notation

In geometry, orbifold notation (or orbifold signature) is a system, invented by the mathematician William Thurston and promoted by John Conway, for representing types of symmetry groups in two-dimensional spaces of constant curvature.

See Tetrahedron and Orbifold notation

Orbital hybridisation

In chemistry, orbital hybridisation (or hybridization) is the concept of mixing atomic orbitals to form new hybrid orbitals (with different energies, shapes, etc., than the component atomic orbitals) suitable for the pairing of electrons to form chemical bonds in valence bond theory.

See Tetrahedron and Orbital hybridisation

Origami

) is the Japanese art of paper folding.

See Tetrahedron and Origami

Orthocentric tetrahedron

In geometry, an orthocentric tetrahedron is a tetrahedron where all three pairs of opposite edges are perpendicular. Tetrahedron and orthocentric tetrahedron are tetrahedra.

See Tetrahedron and Orthocentric tetrahedron

Orthographic projection

Orthographic projection (also orthogonal projection and analemma) is a means of representing three-dimensional objects in two dimensions.

See Tetrahedron and Orthographic projection

Parallelepiped

In geometry, a parallelepiped is a three-dimensional figure formed by six parallelograms (the term rhomboid is also sometimes used with this meaning). Tetrahedron and parallelepiped are Prismatoid polyhedra.

See Tetrahedron and Parallelepiped

Partial differential equation

In mathematics, a partial differential equation (PDE) is an equation which computes a function between various partial derivatives of a multivariable function.

See Tetrahedron and Partial differential equation

Perpendicular

In geometry, two geometric objects are perpendicular if their intersection forms right angles (angles that are 90 degrees or π/2 radians wide) at the point of intersection called a foot.

See Tetrahedron and Perpendicular

Phase diagram

A phase diagram in physical chemistry, engineering, mineralogy, and materials science is a type of chart used to show conditions (pressure, temperature, etc.) at which thermodynamically distinct phases (such as solid, liquid or gaseous states) occur and coexist at equilibrium.

See Tetrahedron and Phase diagram

Piero della Francesca

Piero della Francesca (– 12 October 1492) was an Italian painter of the Early Renaissance.

See Tetrahedron and Piero della Francesca

Planar graph

In graph theory, a planar graph is a graph that can be embedded in the plane, i.e., it can be drawn on the plane in such a way that its edges intersect only at their endpoints.

See Tetrahedron and Planar graph

Plateau's laws

Plateau's laws describe the structure of soap films.

See Tetrahedron and Plateau's laws

Plato

Plato (Greek: Πλάτων), born Aristocles (Ἀριστοκλῆς; – 348 BC), was an ancient Greek philosopher of the Classical period who is considered a foundational thinker in Western philosophy and an innovator of the written dialogue and dialectic forms.

See Tetrahedron and Plato

Platonic solid

In geometry, a Platonic solid is a convex, regular polyhedron in three-dimensional Euclidean space. Tetrahedron and Platonic solid are platonic solids.

See Tetrahedron and Platonic solid

Point groups in three dimensions

In geometry, a point group in three dimensions is an isometry group in three dimensions that leaves the origin fixed, or correspondingly, an isometry group of a sphere.

See Tetrahedron and Point groups in three dimensions

Point reflection

In geometry, a point reflection (also called a point inversion or central inversion) is a transformation of affine space in which every point is reflected across a specific fixed point.

See Tetrahedron and Point reflection

Polygon

In geometry, a polygon is a plane figure made up of line segments connected to form a closed polygonal chain.

See Tetrahedron and Polygon

Polygon mesh

In 3D computer graphics and solid modeling, a polygon mesh is a collection of, s and s that defines the shape of a polyhedral object.

See Tetrahedron and Polygon mesh

Polyhedral graph

In geometric graph theory, a branch of mathematics, a polyhedral graph is the undirected graph formed from the vertices and edges of a convex polyhedron.

See Tetrahedron and Polyhedral graph

Polyhedron

In geometry, a polyhedron (polyhedra or polyhedrons) is a three-dimensional shape with flat polygonal faces, straight edges and sharp corners or vertices.

See Tetrahedron and Polyhedron

Polytope compound

In geometry, a polyhedral compound is a figure that is composed of several polyhedra sharing a common centre.

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Projection (linear algebra)

In linear algebra and functional analysis, a projection is a linear transformation P from a vector space to itself (an endomorphism) such that P\circ P.

See Tetrahedron and Projection (linear algebra)

Pyramid (geometry)

In geometry, a pyramid is a polyhedron formed by connecting a polygonal base and a point, called the apex. Tetrahedron and pyramid (geometry) are Prismatoid polyhedra, pyramids (geometry) and self-dual polyhedra.

See Tetrahedron and Pyramid (geometry)

Pyraminx

The Pyraminx is a regular tetrahedron puzzle in the style of Rubik's Cube. Tetrahedron and Pyraminx are tetrahedra.

See Tetrahedron and Pyraminx

Pyramorphix

The Pyramorphix, also called Pyramorphinx, is a tetrahedral puzzle similar to the Rubik's Cube. Tetrahedron and Pyramorphix are tetrahedra.

See Tetrahedron and Pyramorphix

Pythagorean Triangles

Pythagorean Triangles is a book on right triangles, the Pythagorean theorem, and Pythagorean triples.

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Quaternions and spatial rotation

Unit quaternions, known as ''versors'', provide a convenient mathematical notation for representing spatial orientations and rotations of elements in three dimensional space.

See Tetrahedron and Quaternions and spatial rotation

Rectangle

In Euclidean plane geometry, a rectangle is a quadrilateral with four right angles.

See Tetrahedron and Rectangle

Rectification (geometry)

In Euclidean geometry, rectification, also known as critical truncation or complete-truncation, is the process of truncating a polytope by marking the midpoints of all its edges, and cutting off its vertices at those points.

See Tetrahedron and Rectification (geometry)

Regular 4-polytope

In mathematics, a regular 4-polytope or regular polychoron is a regular four-dimensional polytope.

See Tetrahedron and Regular 4-polytope

Regular graph

In graph theory, a regular graph is a graph where each vertex has the same number of neighbors; i.e. every vertex has the same degree or valency.

See Tetrahedron and Regular graph

Regular polygon

In Euclidean geometry, a regular polygon is a polygon that is direct equiangular (all angles are equal in measure) and equilateral (all sides have the same length).

See Tetrahedron and Regular polygon

Resistor

A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element.

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Rhombohedron

In geometry, a rhombohedron (also called a rhombic hexahedron or, inaccurately, a rhomboid) is a special case of a parallelepiped in which all six faces are congruent rhombi. Tetrahedron and rhombohedron are Prismatoid polyhedra.

See Tetrahedron and Rhombohedron

Right angle

In geometry and trigonometry, a right angle is an angle of exactly 90 degrees or radians corresponding to a quarter turn.

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Role-playing

Role-playing or roleplaying is the changing of one's behaviour to assume a role, either unconsciously to fill a social role, or consciously to act out an adopted role.

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Royal Game of Ur

The Royal Game of Ur is a two-player strategy race board game of the tables family that was first played in ancient Mesopotamia during the early third millennium BC.

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Rubik's Cube

The Rubik's Cube is a 3D combination puzzle invented in 1974 by Hungarian sculptor and professor of architecture Ernő Rubik.

See Tetrahedron and Rubik's Cube

Schläfli orthoscheme

In geometry, a Schläfli orthoscheme is a type of simplex.

See Tetrahedron and Schläfli orthoscheme

Schläfli symbol

In geometry, the Schläfli symbol is a notation of the form \ that defines regular polytopes and tessellations.

See Tetrahedron and Schläfli symbol

Schoenflies notation

The Schoenflies (or Schönflies) notation, named after the German mathematician Arthur Moritz Schoenflies, is a notation primarily used to specify point groups in three dimensions.

See Tetrahedron and Schoenflies notation

Semiconductor

A semiconductor is a material that has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass.

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Silicon

Silicon is a chemical element; it has symbol Si and atomic number 14.

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Simplex

In geometry, a simplex (plural: simplexes or simplices) is a generalization of the notion of a triangle or tetrahedron to arbitrary dimensions.

See Tetrahedron and Simplex

Skew lines

In three-dimensional geometry, skew lines are two lines that do not intersect and are not parallel.

See Tetrahedron and Skew lines

Slope

In mathematics, the slope or gradient of a line is a number that describes the direction and steepness of the line.

See Tetrahedron and Slope

Solder

Solder (NA) is a fusible metal alloy used to create a permanent bond between metal workpieces.

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Solid-state electronics

Solid-state electronics are semiconductor electronics: electronic equipment that use semiconductor devices such as transistors, diodes and integrated circuits (ICs).

See Tetrahedron and Solid-state electronics

Space frame

In architecture and structural engineering, a space frame or space structure (3D truss) is a rigid, lightweight, truss-like structure constructed from interlocking struts in a geometric pattern.

See Tetrahedron and Space frame

Special right triangle

A special right triangle is a right triangle with some regular feature that makes calculations on the triangle easier, or for which simple formulas exist.

See Tetrahedron and Special right triangle

Spherical polyhedron

In geometry, a spherical polyhedron or spherical tiling is a tiling of the sphere in which the surface is divided or partitioned by great arcs into bounded regions called spherical polygons.

See Tetrahedron and Spherical polyhedron

Spieker circle

In geometry, the incircle of the medial triangle of a triangle is the Spieker circle, named after 19th-century German geometer Theodor Spieker.

See Tetrahedron and Spieker circle

Square

In Euclidean geometry, a square is a regular quadrilateral, which means that it has four sides of equal length and four equal angles (90-degree angles, π/2 radian angles, or right angles).

See Tetrahedron and Square

Stanley Kubrick

Stanley Kubrick (July 26, 1928 – March 7, 1999) was an American film director, screenwriter, producer, and photographer.

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Stellated octahedron

The stellated octahedron is the only stellation of the octahedron.

See Tetrahedron and Stellated octahedron

Steradian

The steradian (symbol: sr) or square radian is the unit of solid angle in the International System of Units (SI).

See Tetrahedron and Steradian

Stereographic projection

In mathematics, a stereographic projection is a perspective projection of the sphere, through a specific point on the sphere (the pole or center of projection), onto a plane (the projection plane) perpendicular to the diameter through the point.

See Tetrahedron and Stereographic projection

Symmetric graph

In the mathematical field of graph theory, a graph is symmetric (or arc-transitive) if, given any two pairs of adjacent vertices and of, there is an automorphism such that In other words, a graph is symmetric if its automorphism group acts transitively on ordered pairs of adjacent vertices (that is, upon edges considered as having a direction).

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Symmetric group

In abstract algebra, the symmetric group defined over any set is the group whose elements are all the bijections from the set to itself, and whose group operation is the composition of functions.

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Symmetry group

In group theory, the symmetry group of a geometric object is the group of all transformations under which the object is invariant, endowed with the group operation of composition.

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Symmetry in mathematics

Symmetry occurs not only in geometry, but also in other branches of mathematics.

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Symmetry number

The symmetry number or symmetry order of an object is the number of different but indistinguishable (or equivalent) arrangements (or views) of the object, that is, it is the order of its symmetry group.

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Synergetics (Fuller)

Synergetics is the empirical study of systems in transformation, with an emphasis on whole system behaviors unpredicted by the behavior of any components in isolation.

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Szilassi polyhedron

In geometry, the Szilassi polyhedron is a nonconvex polyhedron, topologically a torus, with seven hexagonal faces.

See Tetrahedron and Szilassi polyhedron

Tales of Symphonia

is an action role-playing video game developed by Namco Tales Studio and published by Namco for the GameCube.

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Tangent

In geometry, the tangent line (or simply tangent) to a plane curve at a given point is, intuitively, the straight line that "just touches" the curve at that point.

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Telecommunications engineering

Telecommunications engineering is a subfield of electronics engineering which seeks to design and devise systems of communication at a distance.

See Tetrahedron and Telecommunications engineering

Tetragonal disphenoid honeycomb

The tetragonal disphenoid tetrahedral honeycomb is a space-filling tessellation (or honeycomb) in Euclidean 3-space made up of identical tetragonal disphenoidal cells. Tetrahedron and tetragonal disphenoid honeycomb are tetrahedra.

See Tetrahedron and Tetragonal disphenoid honeycomb

Tetrahedral hypothesis

The tetrahedral hypothesis is an obsolete scientific theory attempting to explain the arrangement of the Earth's continents and oceans by referring to the geometry of a tetrahedron. Tetrahedron and tetrahedral hypothesis are tetrahedra.

See Tetrahedron and Tetrahedral hypothesis

Tetrahedral kite

A tetrahedral kite is a multicelled rigid box kite composed of tetrahedrally shaped cells to create a kind of tetrahedral truss. Tetrahedron and tetrahedral kite are tetrahedra.

See Tetrahedron and Tetrahedral kite

Tetrahedral molecular geometry

In a tetrahedral molecular geometry, a central atom is located at the center with four substituents that are located at the corners of a tetrahedron. Tetrahedron and tetrahedral molecular geometry are tetrahedra.

See Tetrahedron and Tetrahedral molecular geometry

Tetrahedral number

A tetrahedral number, or triangular pyramidal number, is a figurate number that represents a pyramid with a triangular base and three sides, called a tetrahedron. Tetrahedron and tetrahedral number are tetrahedra.

See Tetrahedron and Tetrahedral number

Tetrahedral symmetry

A regular tetrahedron, an example of a solid with full tetrahedral symmetry A regular tetrahedron has 12 rotational (or orientation-preserving) symmetries, and a symmetry order of 24 including transformations that combine a reflection and a rotation. Tetrahedron and tetrahedral symmetry are tetrahedra.

See Tetrahedron and Tetrahedral symmetry

Tetrahedral-octahedral honeycomb

The tetrahedral-octahedral honeycomb, alternated cubic honeycomb is a quasiregular space-filling tessellation (or honeycomb) in Euclidean 3-space.

See Tetrahedron and Tetrahedral-octahedral honeycomb

Tetrahedrane

Tetrahedrane is a hypothetical platonic hydrocarbon with chemical formula and a tetrahedral structure. Tetrahedron and Tetrahedrane are tetrahedra.

See Tetrahedron and Tetrahedrane

Tetrahedron

In geometry, a tetrahedron (tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertices. Tetrahedron and tetrahedron are deltahedra, individual graphs, platonic solids, Prismatoid polyhedra, pyramids (geometry), self-dual polyhedra and tetrahedra.

See Tetrahedron and Tetrahedron

Tetrahedron (journal)

Tetrahedron is a weekly peer-reviewed scientific journal covering the field of organic chemistry.

See Tetrahedron and Tetrahedron (journal)

Tetrahedron packing

In geometry, tetrahedron packing is the problem of arranging identical regular tetrahedra throughout three-dimensional space so as to fill the maximum possible fraction of space. Tetrahedron and tetrahedron packing are tetrahedra.

See Tetrahedron and Tetrahedron packing

The American Mathematical Monthly

The American Mathematical Monthly is a mathematical journal founded by Benjamin Finkel in 1894.

See Tetrahedron and The American Mathematical Monthly

Thomson problem

The objective of the Thomson problem is to determine the minimum electrostatic potential energy configuration of electrons constrained to the surface of a unit sphere that repel each other with a force given by Coulomb's law.

See Tetrahedron and Thomson problem

Three-dimensional space

In geometry, a three-dimensional space (3D space, 3-space or, rarely, tri-dimensional space) is a mathematical space in which three values (coordinates) are required to determine the position of a point.

See Tetrahedron and Three-dimensional space

Trapezohedron

In geometry, an trapezohedron, -trapezohedron, -antidipyramid, -antibipyramid, or -deltohedron Remarks: the faces of a deltohedron are deltoids; a (non-twisted) kite or deltoid can be dissected into two isosceles triangles or "deltas" (Δ), base-to-base.

See Tetrahedron and Trapezohedron

Tree (graph theory)

In graph theory, a tree is an undirected graph in which any two vertices are connected by path, or equivalently a connected acyclic undirected graph.

See Tetrahedron and Tree (graph theory)

Triangle

A triangle is a polygon with three corners and three sides, one of the basic shapes in geometry.

See Tetrahedron and Triangle

Triangular bipyramid

In geometry, the triangular bipyramid is the hexahedron with six triangular faces, constructed by attaching two tetrahedra face-to-face. Tetrahedron and triangular bipyramid are deltahedra.

See Tetrahedron and Triangular bipyramid

Trirectangular tetrahedron

In geometry, a trirectangular tetrahedron is a tetrahedron where all three face angles at one vertex are right angles. Tetrahedron and trirectangular tetrahedron are tetrahedra.

See Tetrahedron and Trirectangular tetrahedron

Trivial group

In mathematics, a trivial group or zero group is a group consisting of a single element.

See Tetrahedron and Trivial group

Uniform polyhedron

In geometry, a uniform polyhedron has regular polygons as faces and is vertex-transitive—there is an isometry mapping any vertex onto any other.

See Tetrahedron and Uniform polyhedron

Unit sphere

In mathematics, a unit sphere is a sphere of unit radius: the set of points at Euclidean distance 1 from some center point in three-dimensional space.

See Tetrahedron and Unit sphere

Valence (chemistry)

In chemistry, the valence (US spelling) or valency (British spelling) of an atom is a measure of its combining capacity with other atoms when it forms chemical compounds or molecules.

See Tetrahedron and Valence (chemistry)

Vertex (geometry)

In geometry, a vertex (vertices or vertexes) is a point where two or more curves, lines, or edges meet or intersect.

See Tetrahedron and Vertex (geometry)

Vertex figure

In geometry, a vertex figure, broadly speaking, is the figure exposed when a corner of a polyhedron or polytope is sliced off.

See Tetrahedron and Vertex figure

Wacław Sierpiński

Wacław Franciszek Sierpiński (14 March 1882 – 21 October 1969) was a Polish mathematician.

See Tetrahedron and Wacław Sierpiński

Water

Water is an inorganic compound with the chemical formula.

See Tetrahedron and Water

Wedge (geometry)

In solid geometry, a wedge is a polyhedron defined by two triangles and three trapezoid faces. Tetrahedron and wedge (geometry) are Prismatoid polyhedra.

See Tetrahedron and Wedge (geometry)

Wheel graph

In the mathematical discipline of graph theory, a wheel graph is a graph formed by connecting a single universal vertex to all vertices of a cycle.

See Tetrahedron and Wheel graph

William Lowthian Green

William Lowthian Green (13 September 1819 – 7 December 1890) was an English adventurer and merchant who later became cabinet minister in the Kingdom of Hawaii.

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Wythoff construction

In geometry, a Wythoff construction, named after mathematician Willem Abraham Wythoff, is a method for constructing a uniform polyhedron or plane tiling.

See Tetrahedron and Wythoff construction

2001: A Space Odyssey

2001: A Space Odyssey is a 1968 epic science fiction film produced and directed by Stanley Kubrick.

See Tetrahedron and 2001: A Space Odyssey

3-sphere

In mathematics, a 3-sphere, glome or hypersphere is a higher-dimensional analogue of a sphere.

See Tetrahedron and 3-sphere

5-cell

In geometry, the 5-cell is the convex 4-polytope with Schläfli symbol.

See Tetrahedron and 5-cell

See also

Deltahedra

Platonic solids

Prismatoid polyhedra

Pyramids (geometry)

Self-dual polyhedra

Tetrahedra

References

[1] https://en.wikipedia.org/wiki/Tetrahedron

Also known as 0 20 polytope, 1 01 polytope, 1 10 polytope, 12-point sphere, 3-demicube, 3-demihypercube, 3-orthoscheme, 3-simplex, 4-hedron, Alternated cube, Birectangular tetrahedron, Birectified tetrahedron, Half turn tetrahedron, Mirrored sphenoid, Monge point, Order-3 triangular tiling, Phyllic disphenoid, Quadrirectangular tetrahedron, Regular tetrahedron, Scalene tetrahedron, Sphenoid (geometry), Spherical tetrahedron, Tet (geometry), Tetraeder, Tetrahedra, Tetrahedral, Tetrahedral angle, Tetrahedral graph, Tetrahedran, Tetrahedrons, Triangular pyramid, Twelve-point sphere.

, Determinant, Dice, Digon, Dihedral angle, Disphenoid, Dissection into orthoschemes, Distance-regular graph, Distance-transitive graph, Dodecahedron, Dover Publications, Dual polyhedron, Edge (geometry), Electromagnetic field, Electromagnetism, Elliptic geometry, Equilateral triangle, Euclidean geometry, Euler line, Face (geometry), Finite element method, Fire (classical element), Forum Geometricorum, Four-dimensional space, Four-sided die, Fundamental domain, Gaspard Monge, Geometric median, Geometry, Golden ratio, Goursat tetrahedron, Graph (discrete mathematics), HAL 9000, Hamiltonian path, Handedness, Heron's formula, Heronian tetrahedron, Hilbert's third problem, Hill tetrahedron, Honeycomb (geometry), Hosohedron, Hyperbolic space, Incircle and excircles, Inscribed sphere, Isomorphism, Isosceles triangle, Johannes Kepler, K-vertex-connected graph, Kaleidocycle, Kaleidoscope, Klein four-group, Law of cosines, Law of sines, List of spherical symmetry groups, Lone pair, Lorenz Leonard Lindelöf, Marvin Minsky, Mathematical Association of America, Mathematics Magazine, Möbius configuration, Median (geometry), Methane, Midsphere, Mirror image, Monolith (Space Odyssey), Murakami–Yano formula, N-skeleton, Naval architecture, Net (polyhedron), Nicolo Tartaglia, Nine-point circle, Numerical analysis, Octahedron, Orbifold notation, Orbital hybridisation, Origami, Orthocentric tetrahedron, Orthographic projection, Parallelepiped, Partial differential equation, Perpendicular, Phase diagram, Piero della Francesca, Planar graph, Plateau's laws, Plato, Platonic solid, Point groups in three dimensions, Point reflection, Polygon, Polygon mesh, Polyhedral graph, Polyhedron, Polytope compound, Projection (linear algebra), Pyramid (geometry), Pyraminx, Pyramorphix, Pythagorean Triangles, Quaternions and spatial rotation, Rectangle, Rectification (geometry), Regular 4-polytope, Regular graph, Regular polygon, Resistor, Rhombohedron, Right angle, Role-playing, Royal Game of Ur, Rubik's Cube, Schläfli orthoscheme, Schläfli symbol, Schoenflies notation, Semiconductor, Silicon, Simplex, Skew lines, Slope, Solder, Solid-state electronics, Space frame, Special right triangle, Spherical polyhedron, Spieker circle, Square, Stanley Kubrick, Stellated octahedron, Steradian, Stereographic projection, Symmetric graph, Symmetric group, Symmetry group, Symmetry in mathematics, Symmetry number, Synergetics (Fuller), Szilassi polyhedron, Tales of Symphonia, Tangent, Telecommunications engineering, Tetragonal disphenoid honeycomb, Tetrahedral hypothesis, Tetrahedral kite, Tetrahedral molecular geometry, Tetrahedral number, Tetrahedral symmetry, Tetrahedral-octahedral honeycomb, Tetrahedrane, Tetrahedron, Tetrahedron (journal), Tetrahedron packing, The American Mathematical Monthly, Thomson problem, Three-dimensional space, Trapezohedron, Tree (graph theory), Triangle, Triangular bipyramid, Trirectangular tetrahedron, Trivial group, Uniform polyhedron, Unit sphere, Valence (chemistry), Vertex (geometry), Vertex figure, Wacław Sierpiński, Water, Wedge (geometry), Wheel graph, William Lowthian Green, Wythoff construction, 2001: A Space Odyssey, 3-sphere, 5-cell.