Tetrahedral prism

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Tetrahedral prism
Tetrahedral prism.png
Schlegel diagram
Type Prismatic uniform 4-polytope
Uniform index 48
Schläfli symbol {3,3}×{} = h{4,3}×{}
s{2,4}×{}
sr{2,2}×{}
Coxeter diagram CDel node 1.pngCDel 3.pngCDel node.pngCDel 3.pngCDel node.pngCDel 2.pngCDel node 1.png = CDel node h.pngCDel 4.pngCDel node.pngCDel 3.pngCDel node.pngCDel 2.pngCDel node 1.png
CDel node h.pngCDel 2x.pngCDel node h.pngCDel 4.pngCDel node.pngCDel 2.pngCDel node 1.png
CDel node h.pngCDel 2x.pngCDel node h.pngCDel 2x.pngCDel node h.pngCDel 2.pngCDel node 1.png
Cells 2 (3.3.3)Tetrahedron.png
4 (3.4.4)Triangular prism.png
Faces 8 {3}
6 {4}
Edges 16
Vertices 8
Vertex configuration Tetrahedral prism verf.png
Equilateral-triangular pyramid
Symmetry group [3,3,2], order 48
[4,2+,2], order 16
[(2,2)+,2], order 8
Properties convex
Tetrahedral prism net.png
Net

In geometry, a tetrahedral prism is a convex uniform 4-polytope. This 4-polytope has 6 polyhedral cells: 2 tetrahedra connected by 4 triangular prisms. It has 14 faces: 8 triangular and 6 square. It has 16 edges and 8 vertices.

It is one of 18 uniform polyhedral prisms created by using uniform prisms to connect pairs of parallel Platonic solids and Archimedean solids.

Images[]

Tetrahedral hyperprism.png
An orthographic projection showing the pair of parallel tetrahedra projected as a quadrilateral divided into yellow and blue triangular faces. Each tetrahedra also have two other uncolored triangles across the opposite diagonal.
Tetrahedral hyperprism Schlegel.png
Transparent Schlegel diagram seen as one tetrahedron nested inside another, with 4 triangular prisms between pairs of triangular faces.
Tetrahedral Prism YZ ZW.gif
Rotating on 2 different planes

Alternative names[]

  1. Tetrahedral dyadic prism (Norman W. Johnson)
  2. Tepe (Jonathan Bowers: for tetrahedral prism)
  3. Tetrahedral hyperprism
  4. Digonal antiprismatic prism
  5. Digonal antiprismatic hyperprism

Structure[]

The tetrahedral prism is bounded by two tetrahedra and four triangular prisms. The triangular prisms are joined to each other via their square faces, and are joined to the two tetrahedra via their triangular faces.

Projections[]

The tetrahedron-first orthographic projection of the tetrahedral prism into 3D space has a tetrahedral projection envelope. Both tetrahedral cells project onto this tetrahedron, while the triangular prisms project to its faces.

The triangular-prism-first orthographic projection of the tetrahedral prism into 3D space has a projection envelope in the shape of a triangular prism. The two tetrahedral cells are projected onto the triangular ends of the prism, each with a vertex that projects to the center of the respective triangular face. An edge connects these two vertices through the center of the projection. The prism may be divided into three non-uniform triangular prisms that meet at this edge; these 3 volumes correspond with the images of three of the four triangular prismic cells. The last triangular prismic cell projects onto the entire projection envelope.

The edge-first orthographic projection of the tetrahedral prism into 3D space is identical to its triangular-prism-first parallel projection.

The square-face-first orthographic projection of the tetrahedral prism into 3D space has a cuboidal envelope (see diagram). Each triangular prismic cell projects onto half of the cuboidal volume, forming two pairs of overlapping images. The tetrahedral cells project onto the top and bottom square faces of the cuboid.

Related polytopes[]

It is the first in an infinite series of uniform antiprismatic prisms.

Convex p-gonal antiprismatic prisms
Name s{2,2}×{} s{2,3}×{} s{2,4}×{} s{2,5}×{} s{2,6}×{} s{2,7}×{} s{2,8}×{} s{2,p}×{}
Coxeter
diagram
CDel node.pngCDel 4.pngCDel node h.pngCDel 2x.pngCDel node h.pngCDel 2.pngCDel node 1.png
CDel node h.pngCDel 2x.pngCDel node h.pngCDel 2x.pngCDel node h.pngCDel 2.pngCDel node 1.png
CDel node.pngCDel 6.pngCDel node h.pngCDel 2x.pngCDel node h.pngCDel 2.pngCDel node 1.png
CDel node h.pngCDel 3.pngCDel node h.pngCDel 2x.pngCDel node h.pngCDel 2.pngCDel node 1.png
CDel node.pngCDel 8.pngCDel node h.pngCDel 2x.pngCDel node h.pngCDel 2.pngCDel node 1.png
CDel node h.pngCDel 4.pngCDel node h.pngCDel 2x.pngCDel node h.pngCDel 2.pngCDel node 1.png
CDel node.pngCDel 10.pngCDel node h.pngCDel 2x.pngCDel node h.pngCDel 2.pngCDel node 1.png
CDel node h.pngCDel 5.pngCDel node h.pngCDel 2x.pngCDel node h.pngCDel 2.pngCDel node 1.png
CDel node.pngCDel 12.pngCDel node h.pngCDel 2x.pngCDel node h.pngCDel 2.pngCDel node 1.png
CDel node h.pngCDel 6.pngCDel node h.pngCDel 2x.pngCDel node h.pngCDel 2.pngCDel node 1.png
CDel node.pngCDel 14.pngCDel node h.pngCDel 2x.pngCDel node h.pngCDel 2.pngCDel node 1.png
CDel node h.pngCDel 7.pngCDel node h.pngCDel 2x.pngCDel node h.pngCDel 2.pngCDel node 1.png
CDel node.pngCDel 16.pngCDel node h.pngCDel 2x.pngCDel node h.pngCDel 2.pngCDel node 1.png
CDel node h.pngCDel 8.pngCDel node h.pngCDel 2x.pngCDel node h.pngCDel 2.pngCDel node 1.png
CDel node.pngCDel 2x.pngCDel p.pngCDel node h.pngCDel 2x.pngCDel node h.pngCDel 2.pngCDel node 1.png
CDel node h.pngCDel p.pngCDel node h.pngCDel 2x.pngCDel node h.pngCDel 2.pngCDel node 1.png
Image Digonal antiprismatic prism.png Triangular antiprismatic prism.png Square antiprismatic prism.png Pentagonal antiprismatic prism.png Hexagonal antiprismatic prism.png Heptagonal antiprismatic prism.png Octagonal antiprismatic prism.png 15-gonal antiprismatic prism.png
Vertex
figure
Tetrahedral prism verf.png Tetratetrahedral prism verf.png Square antiprismatic prism verf2.png Pentagonal antiprismatic prism verf.png Hexagonal antiprismatic prism verf.png Heptagonal antiprismatic prism verf.png Octagonal antiprismatic prism verf.png Uniform antiprismatic prism verf.png
Cells 2 s{2,2}
(2) {2}×{}={4}
4 {3}×{}
2 s{2,3}
2 {3}×{}
6 {3}×{}
2 s{2,4}
2 {4}×{}
8 {3}×{}
2 s{2,5}
2 {5}×{}
10 {3}×{}
2 s{2,6}
2 {6}×{}
12 {3}×{}
2 s{2,7}
2 {7}×{}
14 {3}×{}
2 s{2,8}
2 {8}×{}
16 {3}×{}
2 s{2,p}
2 {p}×{}
2p {3}×{}
Net Tetrahedron prism net.png Octahedron prism net.png 4-antiprismatic prism net.png 5-antiprismatic prism net.png 6-antiprismatic prism net.png 7-antiprismatic prism net.png 8-antiprismatic prism net.png 15-gonal antiprismatic prism verf.png

The tetrahedral prism, -131, is first in a dimensional series of uniform polytopes, expressed by Coxeter as k31 series. The tetrahedral prism is the vertex figure for the second, the rectified 5-simplex. The fifth figure is a Euclidean honeycomb, 331, and the final is a noncompact hyperbolic honeycomb, 431. Each uniform polytope in the sequence is the vertex figure of the next.

k31 dimensional figures
n 4 5 6 7 8 9
Coxeter
group
A3A1 A5 D6 E7 = E7+ =E7++
Coxeter
diagram
CDel node.pngCDel 3.pngCDel node.pngCDel 3.pngCDel node 1.pngCDel 2.pngCDel node 1.png CDel nodea.pngCDel 3a.pngCDel nodea.pngCDel 3a.pngCDel nodea.pngCDel 3a.pngCDel branch 10.png CDel nodea.pngCDel 3a.pngCDel nodea.pngCDel 3a.pngCDel nodea.pngCDel 3a.pngCDel branch.pngCDel 3a.pngCDel nodea 1.png CDel nodea.pngCDel 3a.pngCDel nodea.pngCDel 3a.pngCDel nodea.pngCDel 3a.pngCDel branch.pngCDel 3a.pngCDel nodea.pngCDel 3a.pngCDel nodea 1.png CDel nodea.pngCDel 3a.pngCDel nodea.pngCDel 3a.pngCDel nodea.pngCDel 3a.pngCDel branch.pngCDel 3a.pngCDel nodea.pngCDel 3a.pngCDel nodea.pngCDel 3a.pngCDel nodea 1.png CDel nodea.pngCDel 3a.pngCDel nodea.pngCDel 3a.pngCDel nodea.pngCDel 3a.pngCDel branch.pngCDel 3a.pngCDel nodea.pngCDel 3a.pngCDel nodea.pngCDel 3a.pngCDel nodea.pngCDel 3a.pngCDel nodea 1.png
Symmetry [3−1,3,1] [30,3,1] [31,3,1] [32,3,1] [33,3,1] [34,3,1]
Order 48 720 23,040 2,903,040
Graph Tetrahedral prism.png 5-simplex t1.svg Demihexeract ortho petrie.svg Up2 2 31 t0 E7.svg - -
Name −131 031 131 231 331 431

References[]

  • John H. Conway, Heidi Burgiel, Chaim Goodman-Strass, The Symmetries of Things 2008, ISBN 978-1-56881-220-5 (Chapter 26)
  • Norman Johnson Uniform Polytopes, Manuscript (1991)

External links[]

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