Pythagoras's Theorem

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

Then:
 * $a^2 + b^2 = c^2$

Also see

 * Pythagoras's Theorem (Hilbert Space), a generalisation to the context of Hilbert spaces.


 * Definition:Pythagorean Triangle
 * Definition:Pythagorean Triple


 * Sum of Squares of Sine and Cosine