Pythagorean Theorem
How to Use The Pythagorean Theorem
The Formula
The picture below shows the formula for the Pythagorean theorem. In the pictures below, side C is always the hypotenuse . Remember that this formula only applies to right triangles .
Examples of the Pythagorean Theorem
When you use the Pythagorean theorem, just remember that the hypotenuse is always 'C' in the formula above . Look at the following examples to see pictures of the formula.

Video Tutorial on How to Use the Pythagorean Theorem
VIDEO

Step By Step Examples of Using the Pythagorean Theorem
Problem 2)
Use the Pythagorean theorem to calculate the value of X. Round your answer to the nearest tenth.

Remember our steps for how to use this theorem. This problems is like example 2 because we are solving for one of the legs.
Step 1) Identify the legs and the hypotenuse of the right triangle .
The legs have length '9' and 'X'. The hypotenuse is 10.

Step 2) Substitute values into the formula (remember 'c' is the hypotenuse)
A^{2} + B^{2} = C^{2}
9^{2} + X^{2} = 10^{2}
Step 3) Solve for the unknown

Problem 3)
Use the Pythagorean theorem to calculate the value of X. Round your answer to the nearest hundredth..

Remember our steps for how to use this theorem. This problems is like example 2 because we are solving for one of the legs.
Step 1) Identify the legs and the hypotenuse of the right triangle .
The legs have length '10' and 'X'. The hypotenuse is 20.

Step 2) Substitute values into the formula (remember 'c' is the hypotenuse)
A^{2} + B^{2} = C^{2}
10^{2} + X^{2} = 20^{2}
Step 3) Solve for the unknown