A Geometrical Treatise on Conic Sections

auxiliary circle axis becomes bisects the angle called centre chord circle described circle of curvature common cone conic section conjugate diameters constant curve cutting plane diameter directrix distance Draw drawn at right drawn parallel ellipse equal Euclid extremities focal chord foci focus formed given greater Hence hyperbola inscribed intersect Join join SP latus rectum locus major axis manner meet meet the axis meet the ellipse middle point minor normal ordinate parabola parallelogram passes perpendicular point Q position produced produced to meet Prop prove radius ratio rectangle rectangular hyperbola respectively right angles sides similar straight line taken tangent touch triangle vertex