 #### Revision Notes

##### What is pythagoras?

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.

##### What is pythagoras?

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

1. 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.)

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