How do you calculate Pythagoras theorem?

The theorem uses a side called the "hypotenuse" this is the longest side of any triangle. The formula is x= nn + mm (x is the hypotenuse and n and m are the other sides)

Lets say the sides were 3 and 4.

x = 3x3 + 4x4

x = 9 + 16

x = 25. This is NOT the finished result, as we still have to SQUARE ROOT this. 25 square rooted is 5. So the sides are 3, 4 and 5