Pythagoras and square roots

For a right triangle, the squares of the two shorter sides add to the square of the hypotenuse: a² + b² = c². The hypotenuse is opposite the right angle and is the longest side.

This relationship does not apply to every triangle. If you seek a shorter side, subtract the known shorter-side square from the hypotenuse square before taking the square root.

Try it yourself

Sketch a right triangle with legs 5 and 12 and calculate its hypotenuse.