r467	perspective, Pelletier points
r468	Feuerbach hyperbola, tripolar
r623	tripolar, Gergonne line, Nagel point, antiorthic axis, orthic axis
r637	Feuerbach hyperbola, centroid, cevian quotient, perspector, Feuerbach point
r642	circumcircle, excircles, ninecircle, excenters, tangent circles, radical center
r1794	perspective, cevian triangle, side triangle, Feuerbach hyperbola