Category:三角形と円に関する定理

Thales's theorem

Simson line

Cramer–Castillon problem

Japanese theorem for cyclic polygons

Miquel's theorem

Harcourt's theorem

Van Lamoen circle

Euler's theorem in geometry

Carnot's theorem (inradius, circumradius)

Polar circle (geometry)

Griffiths' theorem

Lune of Hippocrates

Fuhrmann circle

Kosnita's theorem

Lester's theorem

Reuschle's theorem

Musselman's theorem

Pompeiu's theorem

Van Schooten's theorem

Conway circle theorem

Thébault's theorem

Six circles theorem

Incenter–excenter lemma