Pythagorean Theorem :The Converse

We all know the Pythagorean theorem: in a right triangle ABC at A we have AB²+,AC²=BC². But what about the opposite? If a triangle ABC satisfies AB²+,AC²=BC², does it guarantee a right angle? Yes — and the proof uses a clever construction: build a right triangle with legs then show it's congruent to the original triangle. Watch as we prove the converse step by step.