## Pythagorean theorem

### Definition

In mathematics, the Pythagorean theorem, also known as Pythagoras' theorem, ... often called the "Pythagorean equation".

### Other forms of the theorem

If c denotes the length of the hypotenuse and a and b denote the lengths of the other two sides, the Pythagorean theorem can be expressed as the Pythagorean equation: $$ a^{2}+b^{2}=c^{2}$$
If the length of both a and b are known, then c can be calculated as $$ c={\sqrt {a^{2}+b^{2}}} $$
If the length of the hypotenuse c and of one side (a or b) are known, then the length of the other side can be calculated as $$ a={\sqrt {c^{2}-b^{2}}} $$ or $$ b={\sqrt {c^{2}-a^{2}}} $$