Davies, Charles, 1798-1876 · New York and Chicago, A. S. Barnes and company · leaf 116
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, BOOK V. OF PLANES AND .THEIR ANGLES.DEFINITIONS. 1. A straight line is perpendicular to a plane, when it is perpendicular to every straight line of the plane which it meetsThe point at which the perpendicular meets the plane, iscalled the foot of the perpendicular. 2. If a straight line…
Geometry · Plane trigonometry
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