REGULAR ICOSAHEDRON CONSISTING OF FIFTEEN LARGE CIRCLES

摘要

PURPOSE:To easily obtain a model which is effective to the study of the structure of a geometrically icosahedron by constituting the regular icosahedron by putting 15 members which are formed by folding a large circle as specified. CONSTITUTION:The large circle 2 is folded to form the member 5 consisting of four right-angled triangular prisms 3 having their vertexes in the center O of the circle. Every two vertexes of the right-angled prisms 3 which have a right angle R are connected two positions, every two vertexes which have a 1st acute angle Al are connected at one position, and every two vertexes which have a 2nd acute angle A2 are connected at one position, namely, at four positions in total. The regular icosahedron 1 is constituted by putting 15 members formed by folding the large circular plate 2 whose reverse surface is colored in black together. In a figure, white triangles show the right-angled prisms 3 and black triangles are spaces 4 of the right-angled prisms 3. Every three vertexes having the 1st acute angle A1 are connected at 20 positions and every five vertexes having the 2nd acute angle A2 are connected at 12 positions, so the members 5 are easily put together.