Video narration
Here’s the Pythagorean theorem, made simple. It works only for a right triangle—a triangle with one 90-degree corner. In a right triangle, the two shorter sides that meet at the right angle are called the legs. Label them a and b. The side across from the right angle is the hypotenuse. It’s always the longest side, and we label it c. The theorem says the areas of the squares on the legs add up to the area of the square on the hypotenuse: a squared plus b squared equals c squared. Written as a² + b² = c². For example, if a is 3 and b is 4, then a² is 9 and b² is 16. Add them: 25. So c² is 25, and c is 5. Remember: no right angle, no Pythagorean theorem.