#include
#include
#define PI 3.1415926
class Shape {
public:
virtual double Area( ) = 0;
};
class trapezoid :public Shape
{private :
double s,x,h;
public:
trapezoid(double a,double b,double c)
{s=a;
x=b;
h=c;
}
double Area(){
return (s+x)*h/2;
};
class Circle :public Shape
{private :
double R;
public :
Circle ( double r) {
R=r;
}
double Area (){
return PI*R*R ;}
};
class Triangle :public Shape
{ private :
double a,h;
public :
Triangle(double x,double y)
{a=x;
h=y;
}
double Area (){
return a*h/2;}
};
void main ()
{
Trapezoid A(3.3,5.5,6);
Shape &ra =A;
ca=ra.Area();
Circle B(3.4);
Shape &rb=B;
ba=rb.Area();
Triangle C(3.6,7.8);
ca=C.Area();
cout << "梯形的面积为："<<ca<<"园的面积为："<#include #define PI 3.1415926class Shape { public: virtual double Area( ) = 0;};class trapezoid:public Shape
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