**Pythagorean theorem**

The *pythagorean theorem* states that,
in a right triangle, if you call the
hypotenuse c and the other 2 sides a and b, then:

c^{2} = a^{2} + b^{2}

For example, in a right triangle that has side a = 3 inches and side
b = 4 inches, then the hypotenuse (side c) = :

c^{2} = 3^{2} + 4^{2} =

c^{2} = 9 + 16 = 25. So c is the , which is 5.

So, now here's a problem for you:

What is the hypotenuse (side c) of a right triangle whose other sides (sides a and b)
are 12 inches and 5 inches?

If you know the hypotenuse and one of the other two sides of a right triangle,
you can use the pythagorean theorem to find the missing side by rearranging
the pythagorean theorem. For example, if you call the missing side "b", then:

b^{2} = c^{2} - a^{2}

Click here
to see a proof of why the pythagorean theorem is true.

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