Place the right angle at the origin. Short leg on x-axis. The forth corner of the square is the point on the hypotenuse where the line y = x intersects. (Draw a diagram!) In this case the hypotenuse is y = -4x/3 + 8 x = -4x/3 + 8 7x/3 = 8 7x = 24 x = 3.428571429