As you can see it is pretty simple to use the Pythagorean Theorem to find the missing side length of a right triangle. Call this new number X for the purpose of this example. How to find the sides of a right triangle.
Use the Pythagorean theorem to solve for the missing length.
For example we know that a. Replace the variables in the theorem with the values of the known sides. Use the Pythagorean theorem to solve for the missing length. The square on the hypotenuse equals the sum of the squares on the other two sides.