Ziwet, Alexander, 1853-1928, Hopkins, Louis Allen, joint author · New York, The Macmillan company · leaf 28
cos a. The positive sense of the axis makes with the vector two angles■whose sum is 2 jr = 360°. As their cosines are the same, itmakes no difference which ofthe two angles is used. With these conventions it isreadily seen that the sum of theprojections of the sides of anopen polygon on any axis is… … 18 PLANE ANALYTIC GEOMETRY [I, § 19 clined at the angles Wi, a^, ••• Wj to the axis I; the closing line PiP^ makes the angle a with /; its projection is P\Pt,; and we have P1P2 cos «!+ PaPs cos ota+PsPi cos a^+PiPs cos 0S4+ P^F^ cos Wj = PlPe = PiPe cos a.For, if the abscissas of Pi, P2, — Pe…
Geometry, Analytic
Internet Archive · Cornell University Library · Public Domain Mark 1.0. Free to use for anything.
