tangency
131Casey's theorem — In mathematics, Casey s theorem, also known as the generalized Ptolemy s theorem, is a theorem in Euclidean geometry named after the Irish mathematician John Casey. Formulation of the theorem Let ,O be a circle of radius ,R. Let ,O 1, O 2, O 3, O …
132Mandart inellipse — In geometry, the Mandart inellipse of a triangle is the inconic having parameters where a, b, and c are sides of the triangle. It is named after H. Mandart, who studied it in two papers published in the late 19th century.[1][2] The center of the… …
