Licks, H. E · New York, D. Van Nostrand company · leaf 58
f the cir- cumference. 69 The trisection of the angle is one of the famous problems of antiquity. It can be solved in many ways, but not by plane geometry, for Euclid allowed no instruments but a straight ruler and the compasses. However, if it be per- mitted to mark or graduate the ruler, the… … so that one edge coincides with C while the end moves along the produced line BD. When the mark on the ruler coincides with the semi-circle put there a point E, then the arc EF is one-third of the arc BC and the angle EAF is one-third of the given angle BAC. The reader can easily supply the…
Mathematical recreations
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