We check to see if it is a right triangle by the Pythagorean theorem. X² + Y² ?=? Z² 27² + 120² ?=? 123² 729 + 14400 ?=? 15129 15129 = 15129 So yes it is a right triangle. Therefore, longest side = hypotenuse = Z = 123 inches side opposite A = X = side adjacent angle B = 27 inches side opposite B = Y = side adjacent angle A = 120 inchesEdwin