Skip to content

Paper Together: sit a paper in a room with your friends.See how it works

Angles – GCSE Maths

Foundation · Grade 2 · Non-calculator

Jump to the questions and answers · Download the worksheet (PDF)

Use angles on a line, around a point, in a triangle and in a quadrilateral to find missing angles — and give the reason each time. It is a Foundation topic, aimed at grade 2. Free questions with answers are on this page.

A handful of facts unlock almost every angle question at this grade. Angles on a straight line add to . Angles around a point add to . Angles in a triangle add to ; in a quadrilateral, . Vertically opposite angles (the ones that make an X) are equal. An equilateral triangle has three angles; an isosceles triangle has two equal base angles.

The method is always: write the fact, write the sum, solve for the missing angle. Fourth angle of a quadrilateral with , and is . Reasons must be written in the accepted phrases — 'angles in a quadrilateral add to ' — because the reason is often a mark of its own.

Do not assume a triangle is isosceles or a line is straight unless the diagram is marked or the question says so. A picture that 'looks like' is not evidence.

Objectives

Key points

Worked examples

Example 1

Two angles on a straight line are 25° and an unknown angle. What is the unknown angle?

2 marks

  1. Angles on a straight line add to 180°, and one angle is 25°.
  2. Subtract: 180 − 25 = 155.
  3. The unknown angle is 155°.

Answer: 155°

Common slips
  • Slip: Angles on a straight line add to 182°, and one angle is 25°. That changes a number from the question, so it answers a different question.
  • Slip: Subtract: 183 − 25 = 155. That changes a number in the working, so the step no longer follows from the one before.
  • Slip: The unknown angle is 159°. That does not match the working above it.

Example 2

A triangle has angles 26° and 30°. What is the third angle?

2 marks

  1. The three angles in a triangle add to 180°. The known angles add to 26 + 30 = 56.
  2. Subtract: 180 − 56 = 124.
  3. The third angle is 124°.

Answer: 124°

Common slips
  • Slip: The three angles in a triangle add to 182°. The known angles add to 26 + 30 = 56. That changes a number from the question, so it answers a different question.
  • Slip: Subtract: 183 − 56 = 124. That changes a number in the working, so the step no longer follows from the one before.
  • Slip: The third angle is 128°. That does not match the working above it.

Example 3

Three angles meet at a point and fill a full turn. Two of them are 90° and 100°. What is the third angle?

2 marks

  1. Angles around a point add to 360°. The known angles add to 90 + 100 = 190.
  2. Subtract: 360 − 190 = 170.
  3. The third angle is 170°.

Answer: 170°

Common slips
  • Slip: Angles around a point add to 362°. The known angles add to 90 + 100 = 190. That changes a number from the question, so it answers a different question.
  • Slip: Subtract: 363 − 190 = 170. That changes a number in the working, so the step no longer follows from the one before.
  • Slip: The third angle is 174°. That does not match the working above it.

Questions and answers

GCSE Maths angles questions and answers. Try each one, then open the answer. Easy questions come first.

Question 1 Easy2 marks

Two angles of a triangle are 40° and 60°. What is the third angle?

Show answer

Answer: 80

  1. Angles in a triangle add to 180°.
  2. The value is 80.
  • M1 — Angles in a triangle add to 180°.
  • A1 — Answer 80

Question 2 Easy2 marks

A straight line is split into 50° and another angle. What is the other angle?

Show answer

Answer: 130

  1. Angles on a straight line add to 180°.
  2. The value is 130.
  • M1 — Angles on a straight line add to 180°.
  • A1 — Answer 130

Question 3 Medium2 marks

Three angles of a quadrilateral are 80°, 90° and 70°. What is the fourth?

Show answer

Answer: 120

  1. Angles in a quadrilateral add to 360°.
  2. The value is 120.
  • M1 — Angles in a quadrilateral add to 360°.
  • A1 — Answer 120

Question 4 Medium2 marks

An isosceles triangle has a vertex angle of 40°. What is one base angle?

Show answer

Answer: 70

  1. The two base angles share what is left from 180°.
  2. The value is 70.
  • M1 — The two base angles share what is left from 180°.
  • A1 — Answer 70

Question 5 Hard2 marks

A pair of co-interior angles meet a transversal. One is 70°. What is the other?

Show answer

Answer: 110

  1. Co-interior angles add to 180°.
  2. The value is 110.
  • M1 — Co-interior angles add to 180°.
  • A1 — Answer 110

Question 6 Hard2 marks

A regular pentagon has an exterior angle of 72°. One interior angle sits next to it on a straight line. What is that interior angle?

Show answer

Answer: 108

  1. The interior and exterior angles on a straight line add to 180°.
  2. The value is 108.
  • M1 — The interior and exterior angles on a straight line add to 180°.
  • A1 — Answer 108

Question 7 Exam-style2 marks

A pair of co-interior angles meet a transversal. One is 71°. What is the other?

Show answer

Answer: 109

  1. Co-interior angles add to 180°.
  2. The value is 109.
  • M1 — Co-interior angles add to 180°.
  • A1 — Answer 109

Common mistakes

Most lost marks on this topic are one slip.

  1. Using 360° for a straight line.

    A straight line is 180°.

  2. Adding the triangle angles to 360°.

    A triangle sums to 180°.

  3. Treating vertically opposite angles as angles that add to 180°.

    Opposite angles are equal. Adjacent ones add to 180°.

Spot the slip

Angles on a straight line add to

  1. 180°
  2. 90°
  3. 360°
Show the slip

180° A straight line is half a full turn.

Exam tips

Printable worksheet

The same questions are in a PDF you can print. Answers start on a later page.

Download worksheet (PDF)

Or use Print in your browser. Answers under each question are included when you print.

Questions students ask

Is Angles Foundation or Higher?

Angles is Foundation, aimed at grade 2.

What is a common slip on Angles?

Using 360° for a straight line. A straight line is 180°.

Where can I get Angles questions and answers?

The questions on this page are free. Open Show answer under each one, or download the worksheet PDF. Start free to practise this topic in the app.

Related topics

More on Angles

Practise Angles free

Start free

AQA-style and Edexcel-style questions. Yumio is not affiliated with, endorsed by or connected to AQA, Pearson Edexcel or any other exam board.

Last updated 9 November 2026.

Next topicPractise free