Category:三角形と円に関する定理

Feuerbach's theorem

Japanese theorem for cyclic polygons

Musselman's theorem

Cramer–Castillon problem

Van Lamoen circle

Six circles theorem

Van Schooten's theorem

Pompeiu's theorem

Euler's theorem in geometry

Carnot's theorem (inradius, circumradius)

Polar circle (geometry)

Thébault's theorem

Lune of Hippocrates

Fuhrmann circle

Kosnita's theorem

Lexell's theorem

Lester's theorem

Harcourt's theorem

Reuschle's theorem

Incenter–excenter lemma

Simson line

Thales's theorem

Miquel's theorem

Griffiths' theorem

Conway circle theorem