Davies, Charles, 1798-1876 · New York and Chicago, A. S. Barnes and company · leaf 116
s of a regular octagon, we ha\o 16x90°-4x90o = 1440o-360°=rl080o:and for each angle l080°--r8=13Sp BOOK IV 115 Regular Polygons. 8. Since the sum of the angles about any point is equal tcfour right angles (Bk. I. TL ii. Cor. 3), it may be observed thaithere are only three kinds of regular polygons,… … Second.- Four squares, in whicheach angle is equal to 90°, and theirsi un to 90° x 4 = 360° n Third.—Three hexagons, in-.vhich each angle is equai to120, and the sum of the threeto 120° X 3 = 360°.
Geometry · Plane trigonometry
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