The Pythagorean Theorem for Kids: a² + b² = c² Explained (Grade 8 Math)

Hi, I'm Luna from DoodleBeez. Today we are learning the Pythagorean theorem. It is a special rule that works for every right triangle, and it helps us find a missing side length.

A right triangle has one square corner, called a right angle. The two sides that make the right angle are the legs, a and b. The longest side, across from the right angle, is the hypotenuse, c.

The theorem says a squared plus b squared equals c squared. Squared means a number times itself. So if you square each leg and add them, you get the hypotenuse squared.

Let's try legs of three and four. Three squared is nine. Four squared is sixteen. Nine plus sixteen is twenty five. What number times itself is twenty five? Five! So the hypotenuse is five.

Another one. Legs of six and eight centimeters. Six squared is thirty six, and eight squared is sixty four. Add them to get one hundred. The square root of one hundred is ten, so the hypotenuse is ten centimeters.

You can also find a missing leg. If the hypotenuse is thirteen and one leg is five, subtract instead. Thirteen squared is one hundred sixty nine. Five squared is twenty five. The difference is one hundred forty four, so the leg is twelve.

Now it's your turn. A right triangle has legs of nine and twelve. Find the hypotenuse. Pause and try. Nine squared is eighty one. Twelve squared is one hundred forty four. The total is two hundred twenty five, so the hypotenuse is fifteen.

Great job! Remember, the theorem only works for right triangles, c is always the longest side, and a squared plus b squared equals c squared. Practice the Pythagorean theorem in Middle School Math at doodlebeez.com. See you next time!