| 摘要 |
PROBLEM TO BE SOLVED: To provide a dot placing ruler in order to draw regular poligonal shapes by which eight kinds of regular poligonal shapes from a regular triangle to a regular decagon of an optional size can be easily drawn. SOLUTION: On a transparent flat circular disk, a hole for dot placing is provided at a location which is the center of regular poligonal shapes and the vertex. Also, holes are radially arranged with uniform intervals. The usage of the holes depending on the kind of a regular poligonal shape is performed by figures of regular poligonal shapes which are drawn while being color-sorted at the central part of the disk and contour lines which are drawn while being color-sorted as well, of hole rows connecting from the vertex of the figures. However, for a regular triangle, a regular octagon, and a regular decagon, there are no figures and contour lines. A regular hexagon can be substituted for the regular triangle. The regular octagon and the regular decagon can be drawn by further dividing the indexing angles of a regular square and a regular pentagon in two respectively. The central lines for the dividing are shown by -8-, -10-.
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