Great triambic icosahedron
| Great triambic icosahedron | Medial triambic icosahedron | |
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| Types | Dual uniform polyhedra | |
| Symmetry group | Ih | |
| Name | Great triambic icosahedron | Medial triambic icosahedron |
| Index references | DU47, W34, 30/59 | DU41, W34, 30/59 |
| Elements | F = 20, E = 60 V = 32 (χ = -8) | F = 20, E = 60 V = 24 (χ = -16) |
| Isohedral faces |  |  |
| Duals |  Great ditrigonal icosidodecahedron |  Ditrigonal dodecadodecahedron |
| Stellation | ||
| Icosahedron: W34 | ||
 Stellation diagram | ||
In geometry, the great triambic icosahedron and medial triambic icosahedron are visually identical dual uniform polyhedra. The exterior surface also represents the De2f2 stellation of the icosahedron. The only way to differentiate these two polyhedra is to mark which intersections between edges are true vertices and which are not. In the above images, true vertices are marked by gold spheres.
The 12 vertices of the convex hull matches the vertex arrangement of an icosahedron.
Great triambic icosahedron
The great triambic icosahedron is the dual of the great ditrigonal icosidodecahedron, U47. It has 20 inverted-hexagonal faces, shaped like a three-bladed propeller. It has 32 vertices: 12 exterior points, and 20 hidden inside. It has 60 edges.
Medial triambic icosahedron
The medial triambic icosahedron is the dual of the ditrigonal dodecadodecahedron, U41. It has 20 faces, each being simple concave isogonal hexagons. It has 24 vertices: 12 exterior points, and 12 hidden inside. It has 60 edges.
Unlike the great triambic icosahedron, the medial triambic icosahedron is topologically a regular polyhedron of index two.[1] By distorting the triambi into regular hexagons, one obtains a quotient space of the hyperbolic order-5 hexagonal tiling:
As a stellation
It is Wenninger's 34th model as his 9th stellation of the icosahedron
See also
References
- ↑ The Regular Polyhedra (of index two), David A. Richter
- Wenninger, Magnus (1974). Polyhedron Models. Cambridge University Press. ISBN 0-521-09859-9.
- Wenninger, Magnus (1983). Dual Models. Cambridge University Press. ISBN 978-0-521-54325-5. MR 730208.
- H.S.M. Coxeter, Regular Polytopes, (3rd edition, 1973), Dover edition, ISBN 0-486-61480-8, 3.6 6.2 Stellating the Platonic solids, pp.96-104
External links
- Weisstein, Eric Wolfgang. "Great triambic icosahedron". MathWorld.
- Weisstein, Eric Wolfgang. "Medial triambic icosahedron". MathWorld.
- gratrix.net Uniform polyhedra and duals
- bulatov.org Medial triambic icosahedron Great triambic icosahedron
| Notable stellations of the icosahedron | |||||||||
| Regular | Uniform duals | Regular compounds | Regular star | Others | |||||
| (Convex) icosahedron | Small triambic icosahedron | Medial triambic icosahedron | Great triambic icosahedron | Compound of five octahedra | Compound of five tetrahedra | Compound of ten tetrahedra | Great icosahedron | Excavated dodecahedron | Final stellation |
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| The stellation process on the icosahedron creates a number of related polyhedra and compounds with icosahedral symmetry. | |||||||||