Pythagoras' theorem is a formula you can use to calculate the length of any of the sides on a right-angled triangle or the distance between two points.

Part of

If you know the length of the hypotenuse and one of the other sides, you can use Pythagoras’ theorem to find the length of the third side.

We can rearrange the formula for Pythagoras’ theorem, in order to make or the subject of the formula:

Work out the length of the line , correct to decimal place.

( decimal place)

- Question
Work out the length of the line , correct to decimal place.

**Method 1**(subtract from both sides)

(find the square root of both sides)

( decimal place)

**Method 2**(find the square root of both sides)

( decimal place)