A treatise on special or elementary geometry (1877)
Olney, Edward, 1827-1887, Olney, Edward, 1827-1887. Elements of trigonometry, plane and spherical · New York : Sheldon · leaf 116
arc AB. For, placing circle N upon M, so that O shall foil on O,and OD on its equal OA, D falls on A, and, since angle O = angle 0. OC takesthe direction OB, and, being equal to it, C falls on B. Hence, DC and AB co-incide and are equal. 203, Cor. 2.—A right angle at the centre intercepts a quarter… … Fig. 153. 204:. Theorein,—In the same or in equal circles, arcs wJiich arein the ratio of tiuo luhole 7iumhers subtend angles at the centre ivhichhave the same ratio, whe?ice the angles are to each other as the arcswhich subtend them. Dem.—In tlie equal circles M and N, let the arcs EF and IH,…
Geometry · Trigonometry
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