Given a right angled triangle, we can find the hypotenuse of a triangle using the Pythagorean theorem which says that c^2 = a^2 + b^2, where a is the length, b is the perpendicular height and c is the hypotenuse. The length of the triangle (l) is x and the height of the triangle is also x. By substituting the values,
c^2 = x^2 + x^2 = 2x^ 2
There are two possible answers to c but the hypotenuse cannot be negative.