Analytic geometry and principles of algebra (1913)
Ziwet, Alexander, 1853-1928, Hopkins, Louis Allen, joint author, Hedrick, E. R. (Earle Raymond), 1876-1943 · New York, The Macmillan Company · leaf 31
The positive sense of the axis (drawn through the initial pointof the vector) makes wdth the vector two angles whose sum is2 TT = 360°. As their cosinesare the same it makes no differ-ence which of the two angles isused. With these conventions it isreadily seen that the sum of theprojections of the… … Fig. 19 I, § 20] COORDINATES 19 the vectors PJ\, ^V^;- ••• l*rJ*(\ ^^^ inclined at the angles«i, lu, ••• «-, to the axis /; the closing line Pil\, makes theangle « with I; its projection is P\P\,] and we have P1P2 cos «i + P.Po cos a., + P3P4 cos «3 + Pj^Pr, cos a^ + P:,Pc, cos <<5 = iV^6 =…
Geometry, Analytic
Internet Archive · Public Domain Mark 1.0. Free to use for anything.
