# Truncated octahedron

(Redirected from Omnitruncated tetrahedron)
Truncated octahedron

Type Archimedean solid
Uniform polyhedron
Elements F = 14, E = 36, V = 24 (χ = 2)
Faces by sides 6{4}+8{6}
Schläfli symbols t{3,4}, tr{3,3}
t0,1{3,4} or t0,1,2{3,3}
Wythoff symbol 2 4 | 3
3 3 2 |
Coxeter diagram
Symmetry group Oh, BC3, [4,3], (*432), order 48
Th, [3,3] and (*332), order 24
Rotation group O, [4,3]+, (432), order 24
Dihedral Angle 4-6:cos(-1/sqrt(3))=125°15'51"
6-6:cos(-1/3)=109°28'16"
References U08, C20, W7
Properties Semiregular convex zonohedron
permutohedron

Colored faces

4.6.6
(Vertex figure)

Tetrakis hexahedron
(dual polyhedron)

Net

In geometry, the truncated octahedron is an Archimedean solid. It has 14 faces (8 regular hexagonal and 6 square), 36 edges, and 24 vertices. Since each of its faces has point symmetry the truncated octahedron is a zonohedron. It is also the Goldberg polyhedron GIV(1,1), containing square and hexagonal faces. Like the cube, it can tile (or "pack") 3-dimensional space, as a permutohedron.

If the original truncated octahedron has unit edge length, its dual tetrakis cube has edge lengths $\tfrac{9}{8}\scriptstyle {\sqrt{2}}$ and $\tfrac{3}{2}\scriptstyle{\sqrt{2}}$.

## Construction

A truncated octahedron is constructed from a regular octahedron with side length 3a by the removal of six right square pyramids, one from each point. These pyramids have both base side length (a) and lateral side length (e) of a, to form equilateral triangles. The base area is then a2. Note that this shape is exactly similar to half an octahedron or Johnson solid J1.

From the properties of square pyramids, we can now find the slant height, s, and the height, h, of the pyramid:

$h = \sqrt{e^2-\frac{1}{2}a^2}=\frac{\sqrt{2}}{2}a$
$s = \sqrt{h^2 + \frac{1}{4}a^2} = \sqrt{\frac{1}{2}a^2 + \frac{1}{4}a^2}=\frac{\sqrt{3}}{2}a$

The volume, V, of the pyramid is given by:

$V = \frac{1}{3}a^2h = \frac{\sqrt{2}}{6}a^3$

Because six pyramids are removed by truncation, there is a total lost volume of $\scriptstyle {\sqrt{2}a^3}$.

## Orthogonal projections

The truncated octahedron has five special orthogonal projections, centered, on a vertex, on two types of edges, and two types of faces: Hexagon, and square. The last two correspond to the B2 and A2 Coxeter planes.

Orthogonal projections
Centered by Vertex Edge
4-6
Edge
6-6
Face
Square
Face
Hexagon
Truncated
octahedron
Hexakis
hexahedron
Projective
symmetry
[2] [2] [2] [4] [6]

## Coordinates

 Orthogonal projection in bounding box (±2,±2,±2) Truncated octahedron with hexagons replaced by 6 coplanar triangles. There are 6 new vertices at: (±1,±1,±1).

All permutations of (0, ±1, ±2) are Cartesian coordinates of the vertices of a truncated octahedron of edge length a = √ 2 centered at the origin. The vertices are thus also the corners of 12 rectangles whose long edges are parallel to the coordinate axes.

The edge vectors have Cartesian coordinates (0,± 1,±1) and permutations of these. The face normals (normalized cross products of edges that share a common vertex) of the 6 square faces are (0,0,±1), (0,±1,0) and (±1,0,0). The face normals of the 8 hexagonal faces are (± 1/√ 3, ± 1/√ 3, ± 1/√3). The dot product between pairs of two face normals is the cosine of the dihedral angle between adjacent faces, either -1/3 or -1/√3. The dihedral angle is approximately 1.910633 rad (109.471 ° ) at edges shared by two hexagons or 2.186276 rad (125.263 ° ) at edges shared by a hexagon and a square.

### Permutohedron

The truncated octahedron can also be represented by even more symmetric coordinates in four dimensions: all permutations of (1, 2, 3, 4) form the vertices of a truncated octahedron in the three-dimensional subspace x + y + z + w = 10. Therefore, the truncated octahedron is the permutohedron of order 4.

## Area and volume

The area A and the volume V of a truncated octahedron of edge length a are:

$A = \left(6+12\sqrt{3}\right) a^2 \approx 26.7846097a^2$
$V = 8\sqrt{2} a^3 \approx 11.3137085a^3.$

## Uniform colorings

There are two uniform colorings, with tetrahedral symmetry and octahedral symmetry:

Octahedral symmetry Tetrahedral symmetry
(Omnitruncated tetrahedron)

122 coloring
Wythoff: 2 4 | 3

123 coloring
Wythoff: 3 3 2 |

## Related polyhedra

The truncated octahedron is one of a family of uniform polyhedra related to the cube and regular octahedron.

Uniform octahedral polyhedra
Symmetry: [4,3], (*432) [4,3]+
(432)
[1+,4,3] = [3,3]
(*332)
[3+,4]
(3*2)
{4,3} t{4,3} r{4,3}
r{31,1}
t{3,4}
t{31,1}
{3,4}
{31,1}
rr{4,3}
s2{3,4}
tr{4,3} sr{4,3} h{4,3}
{3,3}
h2{4,3}
t{3,3}
s{3,4}
s{31,1}

=

=

=
=
or
=
or
=

Duals to uniform polyhedra
V43 V3.82 V(3.4)2 V4.62 V34 V3.43 V4.6.8 V34.4 V33 V3.62 V35

It also exists as the omnitruncate of the tetrahedron family:

Family of uniform tetrahedral polyhedra
Symmetry: [3,3], (*332) [3,3]+, (332)
{3,3} t{3,3} r{3,3} t{3,3} {3,3} rr{3,3} tr{3,3} sr{3,3}
Duals to uniform polyhedra
V3.3.3 V3.6.6 V3.3.3.3 V3.6.6 V3.3.3 V3.4.3.4 V4.6.6 V3.3.3.3.3
Dimensional family of omnitruncated polyhedra and tilings: 4.6.2n
Symmetry
*n32
[n,3]
Spherical Euclidean Compact hyperbolic Paracompact
*232
[2,3]
D3h
*332
[3,3]
Td
*432
[4,3]
Oh
*532
[5,3]
Ih
*632
[6,3]
P6m
*732
[7,3]
*832
[8,3]...
*∞32
[∞,3]
Coxeter
Schläfli

tr{2,3}

tr{3,3}

tr{4,3}

tr{5,3}

tr{6,3}

tr{7,3}

tr{8,3}

tr{∞,3}
Omnitruncated
figure
Vertex figure 4.6.4 4.6.6 4.6.8 4.6.10 4.6.12 4.6.14 4.6.16 4.6.∞
Dual figures
Coxeter
Omnitruncated
duals
Face
configuration
V4.6.4 V4.6.6 V4.6.8 V4.6.10 V4.6.12 V4.6.14 V4.6.16 V4.6.∞
Dimensional family of omnitruncated polyhedra and tilings: 4.2n.2n
Symmetry
*nn2
[n,n]
Spherical Euclidean Compact hyperbolic Paracompact Noncompact
*222
[2,2]
D2h
*332
[3,3]
Td
*442
[4,4]
P4m
*552
[5,5]
*662
[6,6]
*772
[7,7]
*882
[8,8]...
*∞∞2
[∞,∞]

[∞,iπ/λ]
Figure
4.4.4

4.6.6

4.8.8

4.10.10

4.12.12

4.14.14

4.16.16

4.∞.∞

4.∞.∞
Coxeter
Schläfli

tr{2,2}

tr{3,3}

tr{4,4}

tr{5,5}

tr{6,6}

tr{7,7}

tr{8,8}

tr{∞,∞}
Dual
V4.4.4

V4.6.6

V4.8.8

V4.10.10

V4.12.12

V4.14.14

V4.16.16

V4.∞.∞
Coxeter

This polyhedron can be considered a member of a sequence of uniform patterns with vertex figure (4.6.2p) and Coxeter-Dynkin diagram . For p < 6, the members of the sequence are omnitruncated polyhedra (zonohedra), shown below as spherical tilings. For p > 6, they are tilings of the hyperbolic plane, starting with the truncated triheptagonal tiling.

The truncated octahedron is topologically related as a part of sequence of uniform polyhedra and tilings with vertex figures n.6.6, extending into the hyperbolic plane:

Dimensional family of truncated polyhedra and tilings: n.6.6
Symmetry
*n42
[n,3]
Spherical Euclidean Compact hyperbolic Paracompact
*232
[2,3]
D3h
*332
[3,3]
Td
*432
[4,3]
Oh
*532
[5,3]
Ih
*632
[6,3]
P6m
*732
[7,3]

*832
[8,3]...

*∞32
[∞,3]

Order 12 24 48 120
Truncated
figures

2.6.6

3.6.6

4.6.6

5.6.6

6.6.6

7.6.6

8.6.6

∞.6.6
Coxeter
Schläfli

t{3,2}

t{3,3}

t{3,4}

t{3,5}

t{3,6}

t{3,7}

t{3,8}

t{3,∞}
Uniform dual figures
n-kis
figures

V2.6.6

V3.6.6

V4.6.6

V5.6.6

V6.6.6

V7.6.6

V8.6.6

V∞.6.6
Coxeter

The truncated octahedron is topologically related as a part of sequence of uniform polyhedra and tilings with vertex figures 4.2n.2n, extending into the hyperbolic plane:

Dimensional family of truncated polyhedra and tilings: 4.2n.2n
Symmetry
*n42
[n,4]
Spherical Euclidean Compact hyperbolic Paracompact
*242
[2,4]
D4h
*342
[3,4]
Oh
*442
[4,4]
P4m
*542
[5,4]
*642
[6,4]
*742
[7,4]
*842
[8,4]...
*∞42
[∞,4]
Truncated
figures

4.4.4

4.6.6

4.8.8

4.10.10

4.12.12

4.14.14

4.16.16

4.∞.∞
Coxeter
Schläfli

t{2,4}

t{3,4}

t{4,4}

t{5,4}

t{6,4}

t{7,4}

t{8,4}

t{4,∞}
Uniform dual figures
n-kis
figures

V4.4.4

V4.6.6

V4.8.8

V4.10.10

V4.12.12

V4.14.14

V4.16.16

V4.∞.∞
Coxeter

## Related polytopes

The truncated octahedron (bitruncated cube), is first in a sequence of bitruncated hypercubes:

 ... Bitruncated cube Bitruncated tesseract Bitruncated 5-cube Bitruncated 6-cube Bitruncated 7-cube Bitruncated 8-cube

## Tessellations

The truncated octahedron exists in three different convex uniform honeycombs (space-filling tessellations):

The cell-transitive bitruncated cubic honeycomb can also be seen as the Voronoi tessellation of the body-centered cubic lattice. The truncated octahedron is one of five three-dimensional primary parallelohedra.