Enneagonal tegum
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Enneagonal tegum | |
---|---|
Rank | 3 |
Type | Uniform dual |
Notation | |
Bowers style acronym | Et |
Coxeter diagram | m2m9o () |
Elements | |
Faces | 18 isosceles triangles |
Edges | 9+18 |
Vertices | 2+9 |
Vertex figure | 2 enneagons, 9 squares |
Measures (edge length 1) | |
Dihedral angle | |
Central density | 1 |
Number of external pieces | 18 |
Level of complexity | 3 |
Related polytopes | |
Army | Et |
Regiment | Et |
Dual | Enneagonal prism |
Conjugates | Enneagrammic tegum, Great enneagrammic tegum |
Abstract & topological properties | |
Flag count | 108 |
Euler characteristic | 2 |
Surface | Sphere |
Orientable | Yes |
Genus | 0 |
Properties | |
Symmetry | I2(9)×A1, order 36 |
Convex | Yes |
Nature | Tame |
The enneagonal tegum, also called an enneagonal bipyramid, is a tegum with an enneagon as the midsection, constructed as the dual of an enneagonal prism. It has 18 isosceles triangles as faces, with 2 order–9 and 9 order–4 vertices. .
In the variant obtained as the dual of a uniform enneagonal prism, the side edges are times the length of the edges of the base enneagon. Each face has apex angle and base angles . If the base enneagon has edge length 1, its height is .