What Is the Pythagorean Theorem?

The Pythagorean theorem is a fundamental principle in geometry that states the relationship between the three sides of a right-angled triangle. The rule is that the square of the hypotenuse (the side opposite the right angle, labeled 'c') is equal to the sum of the squares of the other two sides (the legs, labeled 'a' and 'b').

The theorem is expressed with the famous formula:

a² + b² = c²

How to Use the Calculator

This calculator can find the length of any missing side of a right-angled triangle.

1. Select whether you want to solve for the hypotenuse (c) or one of the legs (a or b).
2. Enter the lengths of the two known sides into the appropriate fields.
3. The calculator will automatically compute the length of the missing side.

Solving for Each Side

By rearranging the original formula, you can solve for the length of any side. The formulas used by the calculator are shown below.