Point on Parabola
Illustration of a parabola. "If a line PT is drawn from any point P of the curve, bisecting the angle between PF and the perpendicular from P to the directrix, every point of the line PT, except P, is without the curve."
G.A. Wentworth Plane And Solid Geometry (Boston: Ginn & Company, 1899) 414
Courtesy the private collection of Roy Winkelman