From the condition, you have 2 equations x + y = 17. (1) x^2 - y^2 = 17. (2) Factor equation (2) (x+y)*(x-y) = 17. Replace here x+y by 17, based on equation (1). You will get 17*(x-y) = 17, or x-y = 1. Thus, instead of equations (1) and (2), you have much simpler system x + y = 17 (3) x - y = 1 (4) Add the equations, and get 2x - 19, x = 9. Hence, y = 17-9 = 8. ANSWER. The sides of the square are 9 cm and 8 cm.