Frank Chance Team 3 A piece of wire of 10 m is bent into the shape of a square and a circle. Which combination will yield a) maximum area b)minimum area? a) Area = L^2 + (Pi)*r^2 Perimeter = 4*L + 2*(Pi)*r 10 = 4L + 2*(Pi)*r (10-2*(Pi)*r)/4 = L, so L = (5/2) - (Pi*r)/2 A = (2.5-(Pi*r)/2)*(2.5-(Pi*r)/2)+(Pi*r^2) A = 6.25 - 2.5*Pi*r + .25*Pi^2*r^2 + Pi*r^2 so A' = 0 = (-2.5)*Pi + .5*Pi^2*r + 2*Pi*r A'' = (+), so this is a minimum solve for r, which is( r = 5/(Pi + 4)), and substitute into Perimeter equation. solve for L, then, which is (L = 10/(Pi + 4)). So, one would cut the wire @ (4*L) from the end. b) Look at the graph of the area function, with r substituted in. The graph is a parabola and increases to r=infinity. Therefore, the largest possible area is that where the whole wire is bent into a circle.