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How Do I Figure the Long Side of a Right Triangle?

A right angle has one 90 degree angle. The long side of the triangle is located opposite the right angle and is called the hypotenuse. The two shorter sides are called "legs." If you know the length of the legs, you can find the length of the long side using the Pythagorean Theorem. The Theorem is named for Pythagoras, who lived in ancient Greece, but was likely known by the Egyptians for 1,000 years before Pythagoras.

Calculator

Instructions

- 1
  Square each of the legs of the triangle. For example, if you know one side is 7 inches and another is 11 inches, square 7 to get 49 and 11 to get 121.
- 2
  Add the squares of the two numbers. In this example, add 121 plus 49 to get 170.
- 3
  Calculate the square root of the result to find the length of the long side, or hypotenuse of the right triangle. Finishing the example, calculate the square root of 170 to be 13.04, meaning the long side of the triangle equals 13.04 inches.

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