出典:Wiktionary
From Ancient Greek δωδεκάεδρον (dōdekáedron). Equivalent to dodeca- + -hedron.
dodecahedron (複数形 dodecahedra または dodecahedrons)
出典:Wikipedia
出典:『Wikipedia』 (2011/06/18 18:06 UTC 版)
In geometry, a dodecahedron (Greek δωδεκάεδρον, from δώδεκα 'twelve' + εδρον 'base', 'seat' or 'face') is any polyhedron with twelve flat faces, but usually a regular dodecahedron is meant: a Platonic solid. It is composed of 12 regular pentagonal faces, with three meeting at each vertex, and is represented by the Schläfli symbol {5,3}. It has 20 vertices and 30 edges. Its dual polyhedron is the icosahedron, with Schläfli symbol {3,5}.