For conic sections, a line {directrix, conic} goes through generator point and closed curve.
Distance {focal length, conic} from focus to vertex is major diameter.
Line segments {latus rectum} can go through conic-section focus and two conic-section points, whose distances to focus are equal.
Line segments {polar, conic} can connect conic poles.
3-Geometry-Solid-Cone-Conic Section
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Date Modified: 2022.0225