Not to be confused with tetrahedroid, Tetraedron, or Tetrahedron (journal).
Regular tetrahedron
(Click here for rotating model)
Type
Platonic solid
Elements
F = 4, E = 6 V = 4 (χ = 2)
Faces by sides
4{3}
Conway notation
T
Schläfli symbols
{3,3}
h{4,3}, s{2,4}, sr{2,2}
Face configuration
V3.3.3
Wythoff symbol
3 | 2 3 | 2 2 2
Coxeter diagram
=
Symmetry
Td, A3, [3,3], (*332)
Rotation group
T, [3,3]+, (332)
References
U01, C15, W1
Properties
regular, convexdeltahedron
Dihedral angle
70.528779° = arccos(1⁄3)
3.3.3 (Vertex figure)
Self-dual (dual polyhedron)
Net
Tetrahedral objects
3D model of a regular tetrahedron
In geometry, a tetrahedron (pl.: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertices. The tetrahedron is the simplest of all the ordinary convex polyhedra.[1]
The tetrahedron is the three-dimensional case of the more general concept of a Euclidean simplex, and may thus also be called a 3-simplex.
The tetrahedron is one kind of pyramid, which is a polyhedron with a flat polygon base and triangular faces connecting the base to a common point. In the case of a tetrahedron the base is a triangle (any of the four faces can be considered the base), so a tetrahedron is also known as a "triangular pyramid".
Like all convex polyhedra, a tetrahedron can be folded from a single sheet of paper. It has two such nets.[1]
For any tetrahedron there exists a sphere (called the circumsphere) on which all four vertices lie, and another sphere (the insphere) tangent to the tetrahedron's faces.[2]
^ abWeisstein, Eric W. "Tetrahedron". MathWorld.
^Ford, Walter Burton; Ammerman, Charles (1913), Plane and Solid Geometry, Macmillan, pp. 294–295
In geometry, a tetrahedron (pl.: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six...
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is no effective way to make that happen in an extended area. The fire tetrahedron represents the addition of the chemical chain reaction, to the three...
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α {\displaystyle \alpha } between every two of them. Define the Hill tetrahedron Q ( α ) {\displaystyle Q(\alpha )} as follows: Q ( α ) = { c 1 v 1 +...
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