设,BC = 40,AC = 30,∠C = 90°,则AB = 50,AB边上的高CD = 30X40/50 = 24 设矩形的长为x,宽为y,则: x/50 = (24-y)/24 x = 25(24-y)/12 矩形的面积S = xy = y*25(24-y)/12 =25(24y-y�� )/12 =-(y - 12)�� *25/12 + 300 当y = 12时,S最大 = 300(m�� )