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Polydrafter
In recreational mathematics, a polydrafter is a polyform with a 30°–60°–90° right triangle as the base form. This triangle is also called a drafting triangle, hence the name.〔.〕 This triangle is also half of an equilateral triangle, and a polydrafter's cells must consist of halves of triangles in the triangular tiling of the plane; equivalently, when two drafters share an edge that is the middle of their three edge lengths, they must be reflections rather than rotations of each other. Any contiguous subset of halves of triangles in this tiling is allowed, so unlike most polyforms, a polydrafter may have cells joined along unequal edges: a hypotenuse and a short leg.
Polydrafters were invented by Christopher Monckton, who used the name ''polydudes'' for polydrafters that have no cells attached only by the length of a short leg. Monckton's Eternity Puzzle was composed of 209 12-dudes.〔.〕
The term ''polydrafter'' was coined by Ed Pegg, Jr., who also proposed as a puzzle the task of fitting the 14 tridrafters—all possible clusters of three drafters—into a trapezoid whose sides are 2, 3, 2, and 5 times the length of the hypotenuse of a drafter.〔.〕
==Enumerating polydrafters==
Like polyominoes, polydrafters can be enumerated in two ways, depending on whether chiral pairs of polydrafters are counted as one polydrafter or two.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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