Learning objective

Understand and apply circle theorems to find unknown angles and provide explanations. You should use the following properties of circles when justifying your answers: the angle in a semicircle is 90 degrees, and the angle between a tangent and a radius is also 90 degrees.

Read the explanation, check the common trap, then practise with flashcards and questions.

Exam focus

Cambridge IGCSE MathematicsCore Geometry

Study support

Understand this objective

Quick explanation

This point belongs to Circle theorems, especially Circle theorems outcomes.
You need to be able to understand and apply circle theorems to find unknown angles and provide explanations. You should use the following properties of circles when justifying your answers: the angle in a semicircle is 90 degrees, and the angle between a tangent and a radius is also 90 degrees.
The key ideas to know are Calculate, Give, and Explain.
Use the linked flashcards and practice questions to check recall, then practise applying the idea in an exam-style answer.

Key concepts

CalculateGiveExplain

Why it matters

This objective helps connect Circle theorems outcomes to exam-style questions, flashcards, and revision notes for Circle theorems.

Revision tools

Flashcards10 linked cards

Flashcard 1 of 10

Press Space to flip, arrows to move

Practice Questions7 linked questions

Question 1 of 7

Choose an answer, get feedback, then move sideways through the set.

0 of 5 attempted

Paper 2Core or Extended Mathematics2 marks

Description

In circle O, AB is a diameter. Point C is on the circumference of the circle. Angle ACB is to be calculated.

a
Calculate the measure of angle ACB.
Your answer
Aim for approximately 2 distinct marking points.
[2]

Revision notestopic notes

Open the full topic revision notes when you are ready to review this objective in context.

No linked resources are published for this section yet.

Revision hubs