Focal Radii of an Ellipse Small 320×128 Medium 640×255 Large 1024×409 Download TIFF Original 2400×958 | (118.3 KB) Description Illustration of half of an ellipse. "If d denotes the abscissa of a point of an ellipse, r and r' its focal radii, then r'=a+ed, r=a-ed." Keywords center, chords, conic sections, ellipse, ellipses, focal chord, focal radii, foci, focus, major axis, minor axis, oval, ovals, radius, section Galleries Conic Sections: Ellipses Source: G.A. Wentworth Plane And Solid Geometry (Boston: Ginn & Company, 1899) 429
