Help, I don't know how to work with right triangles here.
Let ABC be a right triangle, and let H be the point on side AB so that CH is perpendicular to AB. Prove that (x + h)^2*(y + h)^2 = (a + b)^4.
The relationship should be
ABC is a right-angled triangle, the right angle being at C.
The altitude from C onto AB meets AB at H.
AH = x, HB = y, and CH = h.