You can put this solution on YOUR website! Intuitively, the perimeter should be maximized when the triangle is equilateral, but it seems much harder to prove. By AM-GM, we have
The RHS is a constant, and the LHS is equal to s/2 (since a+b+c = 2s). However the equality case cannot occur since this would imply s = s-a = s-b = s-c, which gives a = b = c = 0.