Category:三角形と円に関する定理

Feuerbach's theorem

Musselman's theorem

Simson line

Lune of Hippocrates

Cramer–Castillon problem

Incenter–excenter lemma

Van Lamoen circle

Harcourt's theorem

Euler's theorem in geometry

Carnot's theorem (inradius, circumradius)

Polar circle (geometry)

Thébault's theorem

Kosnita's theorem

Six circles theorem

Fuhrmann circle

Miquel's theorem

Pompeiu's theorem

Lester's theorem

Reuschle's theorem

Van Schooten's theorem

Japanese theorem for cyclic polygons

Griffiths' theorem

Conway circle theorem

Thales's theorem

Lexell's theorem