Создание классов - C++ - Ответ 3084882

#include <iostream>
#include <math.h>
using namespace std;
//áàçîâûé êëàññ
class Triangle
{ protected:
    double a,b; //2 ñòîðîíû
    double u;   //óãîë
  public:
    Triangle(){}
    virtual ~Triangle(){}
    virtual double S() = 0; //ïëîùàäü
    virtual double P() = 0; //ïåðèìåòð
};
class pryam : public Triangle //ïðÿìîóãîëüíûé òðåóãîëüíèê
{
  public:
    pryam(){}
    virtual ~pryam(){}
    virtual double S(); //ïëîùàäü
    virtual double P(); //ïåðèìåòð
};
double pryam::S()
{
  return 0.5*a*b*sin(u);//?
}
double pryam::P()
{
  double c = sqrt(a*a+b*b-2*a*b*cos(u));//?
  return a+b+c;//?
};
///////////////
class ravbedr : public Triangle
{
public:
    ravbedr(){}
    virtual ~ravbedr(){};
    virtual double S();
    virtual double P();
};
double ravbedr::S()
{
    double c=2*a*b*sin(u/2); 
    double p=(a+b+c)/2;
    return sqrt(p*(p-a)*(p-b)*(p-c));
}
double ravbedr::P()
{
    double c=2*a*b*sin(u/2); 
    return a+b+c;
}
///////////////////
class ravstor : public Triangle
{
public:
    ravstor(){}
    virtual ~ravstor(){}
    virtual double S();
    virtual double P();
};
double ravstor::S()
{
    return 0.43*a*b;
}
double ravstor::P()
{
    return 3*a;
}
int main()
{
  pryam a;
 
}