Bailey, Frederick H. (Frederick Harold), 1865- · Boston, London, Ginn & Co. · leaf 196
angle FPiKi. Now ZKPiT = ZFTPi, since they are the alternate-interior angles of two parallel lines cut by a secant; and wehave just proved /_ FTPj = Z. FP^T. Therefore Z KPiT = Z FPiT, and TPj bisects the angleKPiF. It follows that PiN bisects the angle FPjKi, for a line,through the point of… … Fig. 80. As y^ = 4px is the equation of the parabola, the equation ofits directrix is x = — p. Let the equation of any tangent be y = mx + £- (1) Then, if (2) is the tangent perpendicular to (1), its equation n 1 will be y = mx + —„ where m = , m or y = pm. (2) If tangents (1) and (2) meet at (xj,…
Geometry, Analytic
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