Snyder, Virgil, 1869-1950, Sisam, Charles Herschel, 1879-, Hill, Theodore Preston. Early American mathematics books. CU-BANC · New York, H. Holt and Company · leaf 24
g points. (1,2,0) (1,1,1) (-7,6,2) (0, 2, 4) (1, - 4, 2) (x, y, z) 3. Direction cosines of a line.Let I be any directed line inspace, and let I be a line throughthe origin which has the samedirection. If «, ft y (Fig. 4)are the angles which V makeswith the coordinate axes, theseare also, by… … 6 COORDINATES [CHAP. I. Let P=(a, b, c) be any point on I in the positive direction fromthe origin and let OP = r. Then, from trigonometry, we have \_eo_a _ r>_ b __ _c r r r But r is the diagonal of a rectangular parallelepiped whose edges are OA = a, OB = b, OC=c. Hence, we obtain r = Va2 + b2…
Geometry, Analytic
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