Proof that A^2 + B^2 = C^2 in a right triangle. First for the special case of A = B (denoted 2* A^2 = B^2 in the video) and secondly for the general case.

List of proofs: (it's number 10)
http://www.cut-the-knot.org/pythagoras/

I have recently come across a youtuber who thought the Pythagorean theorem was not true. Hopefully this can help him and other spend their time less wasteful than trying to figure out how they have been "tricked" by math.