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The complete icosahedron is formed from all the cells in the stellation, but only the outermost regions, labelled "13" in the diagram, are visible. The stellation of a polyhedron extends the faces of a polyhedron into infinite planes and generates a new polyhedron that is bounded by these planes as faces and the intersections of these planes as ...
Compound of great icosahedron and stellated dodecahedron Type: stellation and compound: Coxeter diagram: ∪ : Convex hull: Dodecahedron: Polyhedra: 1 great icosahedron 1 great stellated dodecahedron: Faces: 20 triangles 12 pentagrams: Edges: 60 Vertices: 32 Symmetry group: icosahedral (I h)
The truncated great stellated dodecahedron is a degenerate polyhedron, with 20 triangular faces from the truncated vertices, and 12 (hidden) doubled up pentagonal faces ({10/2}) as truncations of the original pentagram faces, the latter forming two great dodecahedra inscribed within and sharing the edges of the icosahedron.
The stellation diagram for the icosahedron with the central triangle marked for the original icosahedron. The Fifty-Nine Icosahedra is a book written and illustrated by H. S. M. Coxeter, P. Du Val, H. T. Flather and J. F. Petrie.
There are 58 stellations of the icosahedron, including the great icosahedron (one of the Kepler–Poinsot polyhedra), and the second and final stellations of the icosahedron. The 59th model in The fifty nine icosahedra is the original icosahedron itself. Many "Miller stellations" cannot be obtained directly by using Kepler's method.
The following year, Arthur Cayley gave the Kepler–Poinsot polyhedra the names by which they are generally known today. A hundred years later, John Conway developed a systematic terminology for stellations in up to four dimensions. Within this scheme the small stellated dodecahedron is just the stellated dodecahedron.
The great triambic icosahedron is the dual of the great ditrigonal icosidodecahedron, U47. It has 20 inverted-hexagonal (triambus) faces, shaped like a three-bladed propeller . It has 32 vertices: 12 exterior points, and 20 hidden inside.
In 1858, Bertrand derived the regular star polyhedra (Kepler–Poinsot polyhedra) by faceting the regular convex icosahedron and dodecahedron. In 1974, Bridge enumerated the more straightforward facetings of the regular polyhedra, including those of the dodecahedron. In 2006, Inchbald described the basic theory of faceting diagrams for polyhedra.