X(2), X(4), X(126), X(193), X(468), X(524), X(671), X(2374)
feet of altitudes
(2SA - a^2) / [(SA - a^2)SA] : : ,
SA / (SA - a^2)^2 : : ,
K209 = pK(X468, X4) is a circular cubic invariant under orthoassociation. See CL019.
Its singular focus is X(5512).
It is an antigonal cubic and a member of the class CL019 of cubics.
K209 is the locus of P such that P, X(193) and the DF-pole of P are collinear. See CL039.