Just remember: A^2 + B^2 = C^2 (^2 = squared or raised to the second). Also. A and B are either of the legs. C is 100% of the time the hypotenuse! The hypotenuse is the longest side of a triangle and will always be located directly across from the right angle symbol (the 90 degrees marker). If there is no marker, then the triangle is not a right angle triangle, and the Pythagorean Theorem cannot be used.