Circle Theorems for GCSE Maths: Explanation, Examples and Questions

Circle theorems form an important part of GCSE geometry, offering a set of rules and properties that help calculate unknown angles and explain relationships in circles.

In Core Maths, students learn key properties such as angles in a semicircle equal 90° and the angle between a tangent and radius is 90°.

Extended Maths explores additional theorems, including the angle at the centre is twice the angle at the circumference, angles in the same segment are equal, cyclic quadrilateral properties, and the alternate segment theorem.

Symmetry rules, like equal chords being equidistant from the centre, also feature in the extended syllabus.

The rest of the guide on circle theorems is not quite ready, but if you already know what you're doing, we have practice questions linked below.