设底直径为D.高为H 则,0.25*3.14*D*D*H=216 要使面料最省即表面积最小.则S表＝2*0.25*3.14*D*D+3.14*D*H取最小值.S表＝0.5*3.14*D*D+864/D＝0.5*3.14*D*D+432/D+432/D>=3倍3次根号（0.5*3.14*432*432）＝199.29平方...