These lessons, with videos, examples and step-by-step solutions help GCSE/IGCSE Maths students learn the circle theorems.

**Related Pages**

Angles In A Circle

Tangents Of Circles And Angles

Circles

More Lessons for GCSE Maths

Math Worksheets

**Circle Theorems 1**

The angle at the centre is twice the angle at the edge for configurations with intersecting lines.

**Circle Theorem 2 (angle is a semi circle)**

The angle in a semi-circle is always 90 degrees.

**Circle Theorems 3 (Angles in the same arc)**

Angles in the same segment are equal. (Bow theorem)

**Circle Theorems 4 (cyclic quads)**

Opposite angles in a cyclic quadrilateral add up to 180 degrees.

**The Alternate Segment Theorem**

The angle between a tangent and a chord is equal to the angle in the alternate segment.

Try the free Mathway calculator and
problem solver below to practice various math topics. Try the given examples, or type in your own
problem and check your answer with the step-by-step explanations.

We welcome your feedback, comments and questions about this site or page. Please submit your feedback or enquiries via our Feedback page.