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The name comes from Ancient Greek εἴκοσι (eíkosi) 'twenty' and ἕδρα (hédra) 'seat'. The plural can be either "icosahedra" ( /- d r ə / ) or "icosahedrons". There are infinitely many non- similar shapes of icosahedra, some of them being more symmetrical than others.
It has icosahedral symmetry (I h) and the same vertex arrangement as a rhombic triacontahedron. This can be seen as the three-dimensional equivalent of the compound of two pentagons ({10/2} "decagram"); this series continues into the fourth dimension as the compound of 120-cell and 600-cell and into higher dimensions as compounds of hyperbolic ...
The 600-cell has icosahedral cross sections of two sizes, and each of its 120 vertices is an icosahedral pyramid; the icosahedron is the vertex figure of the 600-cell. The unit-radius 600-cell has tetrahedral cells of edge length 1 φ {\textstyle {\frac {1}{\varphi }}} , 20 of which meet at each vertex to form an icosahedral pyramid (a 4 ...
Name picture Faces Edges Vertices Vertex configuration icosidodecahedron (quasi-regular: vertex- and edge-uniform) 32: 20 triangles 12 pentagons: 60: 30 3,5,3,5 truncated dodecahedron : 32: 20 triangles 12 decagons: 90 60 3,10,10 truncated icosahedron or commonly football (soccer ball) 32: 12 pentagons 20 hexagons: 90 60 5,6,6 ...
Icosahedral symmetry fundamental domains A soccer ball, a common example of a spherical truncated icosahedron, has full icosahedral symmetry. Rotations and reflections form the symmetry group of a great icosahedron. In mathematics, and especially in geometry, an object has icosahedral symmetry if it has the same symmetries as a regular icosahedron.
For example, in a polyhedron (3-dimensional polytope), a face is a facet, an edge is a ridge, and a vertex is a peak. Vertex figure : not itself an element of a polytope, but a diagram showing how the elements meet.
Lists of shapes cover different types of geometric shape and related topics. They include mathematics topics and other lists of shapes, such as shapes used by drawing or teaching tools. They include mathematics topics and other lists of shapes, such as shapes used by drawing or teaching tools.
List of alchemical substances; List of chemical elements; List of minerals – List of minerals with Wikipedia articles; List of named alloys; List of straight-chain alkanes; Polyatomic ion – Ion containing two or more atoms; Exotic molecule – a compound containing one or more exotic atoms