设园半径rr^2=5.6^2+(r-2.5)^2r^2=31.36+r^2-5r+6.255r=67.61r=13.522中心角＝2asin5.6/13.522＝2asin0.41414＝2x24.465=48.93度扇形面积 13.522x13.522x3.14x48.93/360=78三角面积 1/2x11.2x(13.522-2.5)=5.6x11.02...