# Trigometric Ratios Math Review and Tutorial

math tutorials > trig ratios math review

## Introduction to Trig Ratios

We can use Pythagoras' Theorem to
calculate the length of an unknown side in a right-angled triangle when
we are given information about the lengths of *2 other sides*.

However, if we are given information about an *angle* (other than the
90 degrees) and *one side* and need to calculate the length of another
side then we use the **trig ratios**.

## Labelling the sides of a right-angled triangle.

We already know the side opposite the right-angle is called the *hypotenuse*.
We label the other 2 sides according to their position relative to the
known angle.

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## The trigonometric ratios.

The 3 trigonometric ratios are called **sine** (sin), **cosine** (cos)
and **tangent** (tan). These ratios apply to right-angled
triangles.

## Trigonometry problems for you to try.

*Solutions :* 1) a) 0.4 (1dp) b) 0.9 (1dp) c) 2.4 (1dp)

2) a) 0.6 b) 0.8 c) 0.75