In a right triangle, the sides that form the right angle are called legs. The side opposite the right angle is the hypotenuse. The lengths of the legs and the hypotenuse are related by the Pythagorean Theorem.

For any right triangle, the sum of the squares of the lengths of the legs equals the square of the length of the hypotenuse.

Formula:
a² + b² = c²

Example:
8² + 6² = 10²

Example

Find the length of the hypotenuse of a right triangle with leg lengths of 12 cm and 16 cm.

a² + b² = c²

12² + 16² = c²

144 + 256 = c²

400 = c²

20 = c

The length of the hypotenuse is 20 cm.

Practice

1.  Find the length of the hypotenuse of a right triangle with leg lengths of 28 inches and 21 inches.