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.

SOH**CAH**TOA

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**