# Video: The Converse of the Pythagorean Theorem

What can the converse of the Pythagorean theorem be used for?

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### Video Transcript

What can the converse of the Pythagorean theorem be used for?

First of all, what is the Pythagorean theorem? When using the Pythagorean theorem, we must begin with a right triangle. If the triangle does not have a 90-degree angle, then the Pythagorean theorem cannot be used. And if we have side lengths 𝐴, 𝐵, and 𝐶, then the square of the longest side — the side across from the 90-degree angle — is equal to the sum of the squares of the shorter sides.

So we wanna know about the converse of the Pythagorean theorem. It’s essentially working in the other direction. Instead of starting with a 90-degree angle in a triangle, the converse will begin with using all three sides of a triangle and then finishing or ending by figuring out if there is indeed a right angle in this triangle.

So what can the converse of the Pythagorean theorem be used for? It can be used for demonstrating that a triangle has a right angle.