For full tracking and unlimited access to thousands of activities for £1 today.
Introduction

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

SOHCAHTOA

 

Example

Use the side lengths of this triangle to state the value of cosθº ?

 

 

Answer

Label the sides adjacent, opposite and hypotenuse in relation to the angle θº.

 

 

SOHCAHTOA

 

The side adjacent to the angle θ has length 3.

The hypotenuse has length 5.

 

The correct trig ratio is COS so cos θº= 3/5