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In geometry, a cube〔English ''cube'' from Old French < Latin ''cubus'' < Greek κύβος (''kubos'') meaning "a cube, a die, vertebra". In turn from PIE '' *keu(b)-'', "to bend, turn".〕 is a three-dimensional solid object bounded by six square faces, facets or sides, with three meeting at each vertex. The cube is the only regular hexahedron and is one of the five Platonic solids and has 12 edges, 6 faces and 8 vertices. The cube is also a square parallelepiped, an equilateral cuboid and a right rhombohedron. It is a regular square prism in three orientations, and a trigonal trapezohedron in four orientations. The cube is dual to the octahedron. It has cubical or octahedral symmetry. ==Orthogonal projections== The ''cube'' has four special orthogonal projections, centered, on a vertex, edges, face and normal to its vertex figure. The first and third correspond to the A2 and B2 Coxeter planes. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「cube」の詳細全文を読む スポンサード リンク
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