Circle theorem may refer to: Any of many theorems related to the circle; often taught as a group in GCSE mathematics. These include: Inscribed angle theorem. Thales' theorem, if A, B and C are points on a circle where the line AC is a diameter of the circle, then the angle ∠ABC is a right angle. Alternate segment theorem. Ptolemy's theorem. The Milne-Thomson circle theorem in fluid dynamics. Five circles theorem Six circles theorem Seven circles theorem Gershgorin circle theorem
See also Clifford's circle theorems Descartes' theorem also known as 'kissing circles' or 'Soddy circles' theorem List of circle topics