Parts of a Right TriangleIn order to understand the Pythagorean Theorem, it's important that you know the different parts of a right triangle. The two sides that form the 90 degree angle are called the legs. These two sides are always the shortest two sides of the right triangle. The side that is across from the right angle is called the hypotenuse. The hypotenuse is always the longest side of the right triangle.
Want an easy way to remember which ones are the legs? If you trace them, they'll form the letter "L" for legs. If you have trouble figuring out which one is the hypotenuse, start at the square that marks the right angle and go across the triangle to the other side  that side will be the hypotenuse. A common mistake is for students to assume that the hypotenuse is always the one that's at a slant, but it just depends on how the triangle was drawn. You could easily rotate the picture and a different side could be slanted. Always look across from the 90 degree angle to find the hypotenuse.

