Truncated icosahedron
| Truncated icosahedral graph | |
|---|---|
6-fold symmetry schlegel diagram
|
|
| Vertices | 60 |
| Edges | 90 |
| Automorphisms | 120 |
| Chromatic number | 2 |
| Properties | Cubic, Hamiltonian, regular, zero-symmetric |
In geometry, the truncated icosahedron is an Archimedean solid, one of 13 convex isogonal nonprismatic solids whose faces are two or more types of regular polygons.
It has 12 regular pentagonal faces, 20 regular hexagonal faces, 60 vertices and 90 edges.
It is the Goldberg polyhedron GV(1,1), containing pentagonal and hexagonal faces.
This geometry is associated with footballs (soccer balls) typically patterned with white hexagons and black pentagons. Geodesic domes such as those whose architecture Buckminster Fuller pioneered are often based on this structure. It also corresponds to the geometry of the fullerene C60 ("buckyball") molecule.
It is used in the cell-transitive hyperbolic space-filling tessellation, the bitruncated order-5 dodecahedral honeycomb.
This polyhedron can be constructed from an icosahedron with the 12 vertices truncated (cut off) such that one third of each edge is cut off at each of both ends. This creates 12 new pentagon faces, and leaves the original 20 triangle faces as regular hexagons. Thus the length of the edges is one third of that of the original edges.
Cartesian coordinates for the vertices of a truncated icosahedron centered at the origin are all even permutations of:
where φ = 1 + √5/2 is the golden mean. Using φ2 = φ + 1 one verifies that all vertices are on a sphere, centered at the origin, with the radius equal to √9φ + 10. The edges have length 2.
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