Bailey, Frederick H. (Frederick Harold), 1865- · Boston, London, Ginn & Co. · leaf 197
nd (2) simultaneously, that Xi = — p and yi = -^ — pm,values which satisfy the equation of the directrix. 182 PLANE ANALYTIC GEOMETRY. As (1) and (2) are any pair of perpendicular tangents, itfollows that any two perpendicular tangents meet on thedirectrix, and the directrix is the locus of the… … Fig. 81. f = Apx (1) is the parabola, x = -p (2) is its directrix, and F (p, 0) is its focus. If Pi(xi, Yi) is any point of the parabola, the equation ofthe tangent through Pj will be, by (1), § 76, y,y = 2p(x + x0. (3) THE PARABOLA. 183 By [14], § 34, the equation of FPj will be y^U2--:ZJh ovy-y,…
Geometry, Analytic
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