| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to reduce the bulk of a roof material during transportation in a unit roof material. SOLUTION: A unit roof material P is designed to place a plurality of same-sized boards one upon the other so that their respective vertical and horizontal sides may be placed in parallel where each of the boards 1 are placed one upon the other more than a half area and shifted one after another for a specified length in the vertical direction and staggered alternately in the vertical direction. In this case, for each of the upper and lower rectangular boards 1 piled up with the roof material P, a circumscribed rectangle A' is considered which is an overlapped part of the lower rectangular boards 1 and the other edge as a side. A point O is inside of the overlapped part and a cross point of a bisector of a vertical angleα, where the sides of the both rectangular boards 1 of the circumscribed rectangular A' cross, and another bisector of the vertically opposite angleγof the vertical angleβof the circumscribed rectangle B'. The B' has a side 1 which is a side of the circumscribed rectangle of the vertical angleβand a side m which projects from the circumscribed rectangle A'. The upper and lower rectangles 1 are connected at the point O. Since the connecting point O is on the bisectors of the anglesαandγ, the length of a and a, b and b are identical to each other as shown in the figure. Therefore, if one board 1 is rotated at 90 degrees against the other board 1, both boards will be one upon the other exactly.
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