Home   >  Worksheets   >  GCSE questions by topic   >  The cosine rule

The cosine rule

Free Printable The cosine rule PDF Worksheets, Revision Guide & GCSE Past Paper Questions (Grade 7)

Download free the cosine rule worksheets (PDF), GCSE maths past paper questions and worked solutions for The cosine rule (7N). This is a Grade 7 geometry topic from the GCSE questions by topic collection for Higher tier GCSE Maths (Edexcel, AQA, OCR and IGCSE).

The free PDF worksheets table below brings together printable question booklets (Qs) and worked answers or mark schemes (Ans) from Maths Genie, Maths4Everyone, Corbett Maths, Maths Made Easy, Dr Frost, 1st Class Maths, Metatutor, Maths Takeaway, Maths DIY, Dr Austin, GCSE Maths Rocket, E Classroom and PMT, along with past paper question booklets.

Below the worksheet links you can read our the cosine rule revision notes and worked examples with diagrams, try real GCSE past paper the cosine rule questions with step-by-step solutions, or download a PDF of all the cosine rule worksheet links.

Free The cosine rule PDF Worksheets & Answers

Grade 7 • Topic 7N
Resource Questions Answers
GCSE past paper questions & solutions
Qs Ans
Graded exam questions & solutions
Qs Ans
GCSE 9–1 practice booklet & solutions
Qs Ans
Practice Questions & answers
Qs Ans
Textbook Exercise & answers
Qs Ans
MME worksheet & model answers
Qs Ans
GCSE worksheet & solutions
Qs Ans
Edexcel exam questions & solutions
Qs Ans
AQA exam questions & solutions
Qs Ans
Topic worksheet & worked solutions
Qs Ans
GCSE Maths Takeaway exam questions
Qs Ans
Exam-style booklet & solutions
Qs Ans
Practice grid / worksheet & answers
Qs Ans
Practice questions & answers
Qs Ans
GCSE topic booklet & answers
Qs Ans
PMT (Edxl)
Edexcel GCSE topic questions & solutions
Qs Ans
PMT (AQA)
AQA GCSE topic questions & solutions
Qs Ans
PMT (IGCSE)
Edexcel IGCSE topic questions & solutions
Qs Ans
Interactive online lesson & practice
Page
Self-marking online worksheet
Page
GCSE Maths Grade 7 Revision Notes & Method

Guide to The cosine rule: Explanation, Diagrams & Worked Examples

Download Printable One Page Guide (PDF)

Explanation:

Use the Cosine Rule when you do not have a complete opposite side-angle pair: either you know 2 sides and the included angle (SAS) and want the third side using a2 = b2 + c2 − 2bc cos A, or you know all 3 sides (SSS) and want an angle using cos A = b2 + c2 − a22bc.

Make sure the side labeled a is always the side directly opposite the angle A in the formula. Remember to take the square root at the end when finding a side length.

Example 1: Find side a when b = 7 cm, c = 10 cm, and included angle A = 58° (3 s.f.).

A B C 58° 7 cm 10 cm a

Solution:

a2 = 72 + 102 − (2 × 7 × 10 × cos 58°)
a2 = 149 − 140 cos 58° = 74.8112...
a = √74.8112... = 8.6493... cm
Answer: a = 8.65 cm (3 s.f.)

Example 2: A triangle has sides 6 cm, 8 cm, and 11 cm. Find the largest angle (1 d.p.).

A A 6 cm 8 cm 11 cm

Solution:

Largest angle A is opposite longest side (a = 11):
cos A = 62 + 82 − 1122 × 6 × 8 = −2196
A = cos−1(−0.21875) = 102.635...°
Answer: 102.6° (1 d.p.)
Scanned GCSE Exam Questions & Worked Solutions

GCSE Past Paper The cosine rule Questions & Answers

Past Paper Example 1 AQA Jun 2025 2H Q18 4 marks
Lines AB, BC, CD and AD form two triangles.
Not drawnaccurately32°9.6 cm2.8 cm4.1 cm4.1 cmADCB
Work out the length of AD.
Worked Solution & Mark Scheme (4 marks)
In bottom isosceles triangle: base angles are both 32°, so vertex angle = 180° – 2(32°) = 116° M1
Vertically opposite angle in top triangle = 116° M1
By Cosine Rule: AD² = 9.6² + 2.8² – 2(9.6)(2.8) cos(116°) = 100 + 23.567 = 123.567 M1
AD = √123.567 ≈ 11.1 cm. A1
Answer: Answer 11.1 cm
Past Paper Example 2 AQA Nov 2022 2H Q24 5 marks
B is 60 miles from A on a bearing of 170°
NAB170°60 milesNot drawnaccurately
A ship sails from A on a bearing of 247°
It travels at a constant speed of 23 mph for 112 hours.
Is the ship now closer to B than it was when it left A?
You **must** show your working.
Worked Solution & Mark Scheme (5 marks)
(Average speed = distance ÷ time)
Distance AC = 23 × 1.5 = 34.5 miles M2
Angle BAC = 247° – 170° = 77° M1
By Cosine Rule: BC² = 60² + 34.5² – 2 × 60 × 34.5 × cos 77° = 3600 + 1190.25 – 931.30 = 3858.95 M1
BC = √3858.95 = 62.1 miles > 60 miles, so No (it is further away). C1
Answer: Distance travelled = 23 × 1.5 = 34.5 miles. Angle at A = 247° – 170° = 77°.
Distance to B = √(60² + 34.5² – 2 × 60 × 34.5 × cos 77°) = 62.1 miles > 60 miles, so No.
Past Paper Example 3 GCSE Nov 2024 3H Q17 4 marks
Here is triangle ABC.
ABC14.6 cm7.9 cm18.2 cm
Work out the area of triangle ABC.
Give your answer correct to 3 significant figures.
Worked Solution & Mark Scheme (4 marks)
cos A = (14.6² + 7.9² – 18.2²) / (2 × 14.6 × 7.9) = –55.67 / 230.68 = –0.24133... ⇒ A = 103.965° M3
Area = 1/2 × 14.6 × 7.9 × sin(103.965°) = 55.967... = 56.0 cm² A1
Answer: 56.0 cm²

← 7M The sine rule

Back to GCSE questions by topic

7P Congruent triangles →