Area

#include "iostream"
#include "cmath"

using namespace std;

class Figure{
protected:
    string TypeFigure;
public:
    Figure(){}
    virtual ~Figure() {}
    string GetTypeFigure() { return TypeFigure; }
    virtual double GetArea() = 0;

};


class Triangle : public Figure{
protected:
    double AB, BC, AC;
public:
    Triangle(){}
    Triangle(double AB, double BC, double AC){
        this->AB = AB;
        this->BC = BC;
        this->AC = AC;
        TypeFigure = "Triangle";
    };
    double GetArea(){
        double p = (AB+BC+AC)/2;
        return sqrt(p*(p-AB)*(p-BC)*(p-AC));
    }
};

class Rectangle : public Figure{
protected:
    double AB, BC;
public:
    Rectangle(){}
    Rectangle(double AB, double BC){
        this->AB = AB;
        this->BC = BC;
        TypeFigure = "Rectangle";
    }
    double GetArea(){
        return AB*BC;
    }
};

class Circle : public Figure{
protected:
    double R;
public:
    Circle(){}
    Circle(double R): R(R) {TypeFigure = "Circle";}
    double GetArea(){
        return M_PI*R*R;
    }
};

int main(){
    string t;
    cout << "What type of figure?" << '\n';
    cin >> t;
    Figure *p;
    if (t == "Triangle"){
        double AB, BC, AC;
        cin >> AB >> BC >> AC;
        p = new Triangle(AB,BC,AC);
    }
    else if (t == "Rectangle"){
        double AB, BC;
        cin >> AB >> BC;
        p = new Rectangle(AB, BC);
    }
    else {
        int r;
        cin >> r;
        p = new Circle(r);
    }
    cout << "Area " << p->GetTypeFigure() <<  " = "<< p->GetArea();
    return 0;
}