Davies, Charles, 1798-1876 · New York and Chicago, A. S. Barnes and company · leaf 100
be equal. Now, these proportions do not hold good in the quadrilate-rals. For, in the square and rectangle, the correspondingangles are equal, but the sides are not proportional; and theangles of a parallelogram or quadrilateral, may be varied atpleasure, without altering the lengths of the sides.… … Proportion 9 of Tiianglee. Let ABC and DEF be two tri-angles having the angle A equal tothe angle D, and AS DE : : AC 1 DF; .hen will the two triangles besimilar. For, lay off AG equal to DE, and through G draw GI parallel to BC. Then the angle AG I will be equal to the angleABC (Bk. I. Th. xiv);…
Geometry · Plane trigonometry
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