# Pythagoras's Theorem/Proof 4

## Theorem

Let $\triangle ABC$ be a right triangle with $c$ as the hypotenuse.

Then:

$a^2 + b^2 = c^2$

## Proof

Dissect the square on the left (which has area $c^2$) as shown.

Rearrange the pieces to make the two squares on the right, with areas $a^2$ and $b^2$.

$\blacksquare$

## Source of Name

This entry was named for Pythagoras of Samos.

## Historical Note

This proof was discovered by Bhaskara II Acharya.

As he is then reported as saying:

Behold!