| 摘要 |
PROBLEM TO BE SOLVED: To allow for trigonometric function calculation, without having to use a function table in the back of a relevant book or the like that has been required conventionally. SOLUTION: A plurality of orthogonal parallel lines are drawn vertically and horizontally, at respective regular intervals on a plane plate. One of the intersection points of the parallel lines is determined to be an origin point. Graduations are marked vertically and horizontally, starting from the origin point respectively. A circular arc line with a radius of unit length from the origin point is drawn, and the principles of trigonometric functions can be easily imaged, and the lengths of the opposite side and the adjacent side to the angle can also be read. Since such a consolidation is made into a single sheet of ruler, the ruler is easy to use and convenient to carry. COPYRIGHT: (C)2007,JPO&INPIT
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