Loney, S. L. (Sidney Luxton), 1860-1939 · London, Macmillan and co. · leaf 321
OCUSBEING THE POLE. 335. Let S be the focus, A the vertex, and ZM thedirectrix; draw SZ perpendicular to ZM. Let ZS be chosen as the positive direction of theinitial line, and produce it to X, Take any point P on thecurve, and let its polar co-ordinates be r and 6, so thatwe have SP = r, and… … = ei- + SP.cosO Therefore r = = l + e.r. cos0.1 1 — 6 008 6^ .(1). THE POLAR EQUATION, FOCUS BEING POLE. 307 This, being the relation holding between the polarcoordinates of any point on the curve, is, by Art. 42, therequired polar equation. Cor. If SZ be taken as the positive direction of the…
Coordinates · Geometry, Analytic
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