Pythagoras was a Greek mathematician who lived over 2500 years ago. He is most famous for Pythagoras’ Theorem, which includes the important formula for right-angled triangles that we are revising here.
The longest side in a right-angled triangle is called the hypotenuse – this will always be the side opposite the right angle.
If we label the hypotenuse c, and label the other two sides a and b:
then Pythagoras’ Theorem tells us that
a2 + b2 = c2
(where a, b, and c are the lengths of the three sides).
Using pythagoras’ theorem
- To find the length of the hypotenuse use:
c = √a2 + b2
(Note that when finding the hypotenuse you add inside the square root.)
2. To find the length of one of the other sides use:
a = √c2 – b2 or b = √c2 – a2
(Note that when finding one of the other sides you subtract inside the square root.)