To solve this, let the dimensions be x and y. We know
that the area is 225. So, x * y = 225
Let the perimeter be denoted as P.
P = 2x + 2y
sine y = 225/x
P = 2x + 450/x
P' = 2 - 450/x^2
P'' = + 900/x^3
Put P' = 0
then x = 15
at x =15 P'' is positive
So the minimum perimeter, will be:
P = 2 (15 + 15) = 60 cm
