# Wikijunior:More on Mathematics/Pythagorean theorem

The **Pythagorean theorem** is the theory that the sum of the square areas of sides A and B add up to the hypotenuse, or C's square area. It's formula is described as:

There are many reasons to prove this correct; you may find them on Wikipedia. However, there is more than just this equation, called the *Pythagorean equation*.

## Pythagorean triples[edit]

Pythagorean triples are three sets of positive whole numbers that can make a perfect triangle.

Take the image on the right. Pretend (A) is 3 and (B) is 4. What is (C)? (Hint: C is the hypotenuse; the longest side on the picture.) Use the Pythagorean equation to figure it out! (Click on the reference link to see the answer!)^{[1]}

Now, let's try the Pythagorean equation backwards! Now, (B) is 12 and (C) is 13. Please figure out (A).^{[2]}