Loading please wait

The smart way to improve grades

Comprehensive & curriculum aligned

Try an activity or get started for free

Finding a Side Length Using Trigonometry (2)

In this worksheet, students use trigonometry to calculate a side length in right-angled triangles.

'Finding a Side Length Using Trigonometry (2)' worksheet

Key stage:  KS 3

Year:  Year 9 Maths worksheets

Curriculum topic:   Geometry and Measures

Curriculum subtopic:   Solve Right-Angled Triangle Problems

Popular topics:   Geometry worksheets

Difficulty level:  

Worksheet Overview

In a right-angled triangle, the sides and the angles are connected by three trigonometric ratios.



The three trig ratios are:



A quick way to remember this is to memorise the word




Using trigonometry, calculate the side length x to 3 sig. figs.




Label the sides adjacent, opposite and hypotenuse in relation to the given angle 54º.

The given sides are the hypotenuse (x) and the adjacent (7).



The correct trig ratio is COS.


Set up the trig equation to get:

cos54º = 7/x

xcos54º = 7

x = 7/cos54º

x = 7 ÷  0.587785252....

x = 11.9 (3 s.f.)

What is EdPlace?

We're your National Curriculum aligned online education content provider helping each child succeed in English, maths and science from year 1 to GCSE. With an EdPlace account you’ll be able to track and measure progress, helping each child achieve their best. We build confidence and attainment by personalising each child’s learning at a level that suits them.

Get started

Popular Maths topics

Try an activity or get started for free