## 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
$$ b={\sqrt {c^{2}-a^{2}}} $$