The Pythagorean Theorem states that if you know two sides of a right triangle, you can find the length of the third side by using the formula a^2 + b^2 = c^2. To use the basic formula, plug the lengths of the two short sides in for a and b and use c for the hypotenuse. You can also find the length of a shorter side if you have one short side and the hypotenuse. Using the theorem backwards, you can determine if the sides of a triangle form a right triangle.
Instructions
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1
Look at the three lengths of the triangle sides in the problem. For our example, we'll evaluate whether a triangle with lengths of 6, 4 and 5 is a right triangle.
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2
Substitute the two shorter sides (4 and 5) in for a and b and 6 in for c to get 4^2 + 5^2 = 6^2.
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3
Square each term to get 16 + 25 = 36. Add 25 and 16 together to get 41, which does not equal 36, so using the theorem the lengths are not sides of a right triangle.