| 摘要 |
An educational entertainment device includes at least one cube formed from (a) a regular tetrahedron and (b) four 1/8th sections of a regular octahedron wherein the faces of the tetrahedron and the faces of the octahedron are all congruent. The 1/8th sections are formed by slicing the octahedron through three orthogonal planes, each slicing plane passing through four vertices of the octahedron, each 1/8th section being defined by (a) one octahedron face and (b) three mutually orthogonal corner faces. By coupling the octahedron face of each of the four 1/8th sections to a corresponding one of the tetrahedron faces in edge-to-edge fashion, one cube is formed. Each side of the cube includes two corner faces, one from each of two 1/8th sections. By rotating a 1/8th section about an axis perpendicular to the plane interfacing the 1/8th section and the tetrahedron, the two corner faces forming a cube side can be altered. A plurality of n3, e.g. eight, cubes can form a block of cubes, in an nxnxn arrangement of cubes. Indicia may be applied to the corner faces of the cubes so that each face of the block has prescribed indicia thereon when (a) all of the 1/8th sections on each cube are rotated in a prescribed fashion and (b) the cubes are arranged relative to each other in a predefined manner. The block, in addition to entertainment use, can be used to show seven planes in space and the nature of the tetrahedron and octahedron as basic structures.
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