class Trapezoid:public Shape { public: Trapezoid(doublea=0,double b=0,double c=0){x=a;y=b;h=c;}; virtualdouble area()const { return(x+y)*h

trapezoid4 平行四边形(Parallelogram)调节 5 梯形(Trapezoid)调节6 枕形/桶形(Pincushion)调节 7 弓形(Balance)也称为平衡调节恢复出厂设置(Return to factory sett