Cambridge IGCSE Mathematics · Syllabus 0580 · Geometry
Circle Theorems II
What is Circle Theorems II?
The three symmetry properties of a circle required by Cambridge IGCSE Mathematics 0580 Extended candidates only, under E4.8: chords of equal length are the same perpendicular distance from the centre; the perpendicular bisector of a chord passes through the centre, so the perpendicular dropped from the centre to a chord bisects it; and the two tangents drawn to a circle from the same external point are equal in length. All three follow from the circle's reflection symmetry rather than from any angle rule.
This definition is part of the Geometry chapter in Cambridge IGCSE Mathematics.