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(unicode:⊗) |- |bgcolor=#e7dcc3|Coxeter–Dynkin diagrams|| |- |bgcolor=#e7dcc3|Symmetry group||D''n''d, (), (2 *''n''), order 4''n'' |- |bgcolor=#e7dcc3|Rotation group||D''n'', ()+, (22''n''), order 2''n'' |- |bgcolor=#e7dcc3|Dual polyhedron||trapezohedron |- |bgcolor=#e7dcc3|Properties||convex, semi-regular vertex-transitive |- |bgcolor=#e7dcc3|Net|| |} In geometry, an ''n''-sided antiprism is a polyhedron composed of two parallel copies of some particular ''n''-sided polygon, connected by an alternating band of triangles. Antiprisms are a subclass of the prismatoids. Antiprisms are similar to prisms except the bases are twisted relative to each other, and that the side faces are triangles, rather than quadrilaterals. In the case of a regular ''n''-sided base, one usually considers the case where its copy is twisted by an angle 180°/''n''. Extra regularity is obtained by the line connecting the base centers being perpendicular to the base planes, making it a right antiprism. As faces, it has the two ''n''-gonal bases and, connecting those bases, 2''n'' isosceles triangles. ==Uniform antiprism== A uniform antiprism has, apart from the base faces, 2''n'' equilateral triangles as faces. As a class, the uniform antiprisms form an infinite series of vertex-uniform polyhedra, as do the uniform prisms. For we have as degenerate case the regular tetrahedron as a ''digonal antiprism'', and for the non-degenerate regular octahedron as a ''triangular antiprism''. The dual polyhedra of the antiprisms are the trapezohedra. Their existence was first discussed and their name was coined by Johannes Kepler. 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「Antiprism」の詳細全文を読む スポンサード リンク
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