inheritance exc

#include<iostream>
#include <cmath>
using namespace std;
class Cpolygon {
    float ribsNumber;
    float side;
    float apothem;
protected:
    double pi = 22.0 / 7.0;
    float radius;
public:
    void setPolygon(float Radius,float RibsNumber ) {
        radius= Radius; ribsNumber = RibsNumber;
        double angle = pi / RibsNumber;
        side = 2 * radius * sin(angle);
        apothem = radius * cos(angle);
    }
    float getRadius() {
        return radius;
    }
    float getRibsNumber() {
        return ribsNumber;
    }
    float getSide() { return side; }
    float getApothem() { return apothem; }
    float polygonArea() {
        return (0.5 * ribsNumber * side * apothem);
    }
    float polygonCirum() {
        return (side * ribsNumber);
    }
};

class circle : public Cpolygon {
public:
    circle(float r) {
        radius = r;
    }
    float circleCirum() {
        return (2 * pi * radius);
    }
    float circleArea() {
        return (pi * radius * radius);
    }
};
class Ccircum : public Cpolygon {


};
int main() {
    circle c(20);
    cout << " my circle radius is :" << c.getRadius() << endl;
    cout << " my circle area is :" << c.circleArea()<<endl;
    cout << " my circle cirum is :" << c.circleCirum()<<endl;
    cout << "\n------------------------------------------\n";
    Cpolygon p;
    p.setPolygon(20,7);
    cout << " my polygon Ribs Number is :" << p.getRibsNumber() << endl;
    cout << " my polygon radius is :"<<p.getRadius() << endl;
    cout << " my polygon side is :" << p.getRadius() << endl;
    cout << " my polygon apothem is :" << p.getApothem() << endl;
    cout << " my polygon area is :" << p.polygonArea() << endl;
    cout << " my polygon cirum is :" << p.polygonCirum() << endl;
}