The sum of the lengths of the two sides given is 15 inches + 18 inches = 33 inches. The Triangle Inequality Theorem states that the sum of the lengths of any two sides of a triangle must be greater than the length of the third side. This means that the length of the third side of the triangle must be less than 33 inches. It also means that the length of the third side of the triangle must be greater than the difference between the lengths of the two sides given, which is 18 inches – 15 inches = 3 inches. Since the third side must have a length of between 3 inches and 33 inches, the third side of the triangle cannot have a length of 36 inches.
