Plane and solid analytic geometry; an elementary textbook (1901)
Ashton, Charles H. (Charles Hamilton), 1866- · New York, C. Scribner's sons · leaf 223
0, y - p sin <f> sin 9, [8] z = p cos <|>. Note. — Spherical coordinates have usually been called polar coordi-nates. But the application of the system described in Art. 6 is morenearly analogous to the uses of polar coordinates in two dimensions. 8. Angle between two lines. — Let av… … Fig. 7.Then by [1] i\p? = (xx - x2y + to - y2y + (ti - *2)2> or by [6] = {p1 cos «x — p2 cos a2)2 -f- (px cos ftx — p2 cos /32)2 + (/>iCOS71-/d2 cos 72)2,or by [7] = p^-\-p2 — 2 pxp2 (cos «x1 cos a 2 + cos /3X cos /52 -J- cos 7X cos72). Ch. I, § 8] COORDINATE SYSTEMS. THE POINT 205 But by the…
Geometry, Analytic
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