Hexahedron

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A hexahedron (plural: hexahedra) is any polyhedron with six faces. A cube, for example, is a regular hexahedron with all its faces square, and three squares around each vertex.

There are seven topologically distinct convex hexahedra,[1] one of which exists in two mirror image forms. (Two polyhedra are "topologically distinct" if they have intrinsically different arrangements of faces and vertices, such that it is impossible to distort one into the other simply by changing the lengths of edges or the angles between edges or faces.)

Quadrilaterally-faced hexahedron (Cuboid) 6 faces, 12 edges, 8 vertices
Hexahedron.png Cuboid.png Trigonal trapezohedron.png Trigonal trapezohedron gyro-side.png Usech kvadrat piramid.png Parallelepiped 2013-11-29.svg Rhombohedron.svg
Cube
(square)
Rectangular cuboid
(three pairs of
rectangles)
Trigonal trapezohedron
(congruent rhombi)
Trigonal trapezohedron
(congruent quadrilaterals)
Quadrilateral frustum
(apex-truncated
square pyramid)
Parallelepiped
(three pairs of
parallelograms)
(three pairs of
rhombi)
Oh, [4,3], (*432)
order 48
D2h, [2,2], (*222)
order 8
D3d, [2+,6], (2*3)
order 12
D3, [2,3]+, (223)
order 6
C4v, [4], (*44)
order 8
Ci, [2+,2+], (×)
order 2
Others
Hexahedron5.svg
Triangular bipyramid
36 Faces
9 E, 5 V
Hexahedron7.svgHexahedron7a.svg
Tetragonal antiwedge. Chiral – exists in "left-handed" and "right-handed" mirror image forms.
4.4.3.3.3.3 Faces
10 E, 6 V
Hexahedron6.svg
4.4.4.4.3.3 Faces
11 E, 7 V
Hexahedron2.svg
Pentagonal pyramid
5.35 Faces
10 E, 6 V
Hexahedron3.svg
5.4.4.3.3.3 Faces
11 E, 7 V
Hexahedron4.svg
5.5.4.4.3.3 Faces
12 E, 8 V

There are three further topologically distinct hexahedra that can only be realised as concave figures:

Concave
Hexahedron8.svg
4.4.3.3.3.3 Faces
10 E, 6 V
Hexahedron10.svg
5.5.3.3.3.3 Faces
11 E, 7 V
Hexahedron9.svg
6.6.3.3.3.3 Faces
12 E, 8 V

References[edit]

  1. ^ Counting polyhedra

See also[edit]

External links[edit]