Question 760438
Longer side = x
Shorter side = x - 3
x^2 + (x-3)^2 = 225
 x^2 + x^2 - 6x + 9 = 225
       2x^2 - 6x - 216 = 0
Divide by 2
         x^2 - 3x - 108 = 0
         (x - 12)(x + 9) = 0
     x = 12     x = -9 (No answer)
 Longer side = 12cm
 Shorter side = 9cm
  12^2 + 9^2 = 225 cm^2
   144 + 81 = 225 cm^2
        225 = 225.
Hope this helps.
:-)