Geometry & MeasuresVery High Exam FrequencyAQAEdexcelOCRWJEC

Circle Theorems

Revise Circle Theorems in Geometry & Measures for GCSE Mathematics with 18 exam-style questions and 5 flashcards. This is a very high-frequency exam topic, so it is worth revising until the core ideas feel automatic.

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The Geometry of Pizza

Introduction 2

The Eight Circle Theorems

Key Facts 3

Solving Circle Theorem Problems

Deep Dive 4

Worked Example: Centre and Circumference

Notes 5

Common Mistakes

Exam Tips

Sample Flashcards

Angle in Semicircle

Any angle inscribed in a semicircle (with diameter as base) is always 90°. Always!

Cyclic Quadrilateral

If all 4 vertices lie on a circle, opposite angles sum to 180°. Also works in reverse: if opposite angles sum to 180°, then it's cyclic!

Sample Questions

AB is a diameter of a circle. Point C lies on the circle. What is the size of angle ACB?

A. 45°
B. 60°
C. 90°
D. 180°

1 markfoundation

State the circle theorem used to find angle x in the diagram, and explain why it applies in this situation.

2 marksstandard

exam-style questions

revision flashcards

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