Открытое наследовние (ООП)

#include <iostream.h>
#include <conio.h>
#include <math.h>
 
class Triangle{
public: Triangle(); ~Triangle();
  LSet(int L) {cout<<"Left side: "; cin>>L;return L;}
  RSet(int R) {cout<<"Right side: "; cin>>R; return R;}
  BSet(int B) {cout<<"Buttom side: "; cin>>B; return B;}
  Perimetr(int L, int R, int B) {P=L+R+B; return P;}
 
protected: int L, R, B, P;};
 
class Equiteral
class Equiteral:class Triangle {
 Square(int L, int R, int B) {S=0.5*B*(B*B-(B/2)*(B/2)); return S;}
protected: int S;};
 
//constructor Triangle
Triangle::Triangle(): int L(5), int R(5), int B(5){};
Triangle::~Triangle() {};
 
 
//constructor Equiteral
Equiteral::Equiteral() {};
Equiteral::~Equiteral() {};
 
 
int main()
{
Triangle(); cout<<"\n\n "<<endl;
Equiteral("Triangle"); cout<<"\n\n "<<endl;
getch(); return 0;
}

#include <iostream>
#include <conio.h>
#include <math>
using namespace std;
 
class Triangle{
 public: Triangle(); ~Triangle();
  double  a, b, c;
  double per, alpha, betta, gamma;
  double Sq, rad1, rad2, rad3;
  double gr1, gr2 , gr3;
 
  double  vvod_a()
        {
        cout<<"\nInsert new a: ";
        cin>>a;
        return a;
        }
  double  vvod_b()
        {
         cout<<"\nInsert new b: ";
         cin>>b;
         return b;
        }
  double  vvod_c()
        {
         cout<<"\nInsert new c: ";
         cin>>c;
          if (a+b<c || a+c<b || b+c<a)
           {
           cout<<"Error!!!"<<endl;
           cout<<"Insert new a, b, c: "<<endl;
 
           cin>>a>>b>>c;
            return a,b,c;
           }
         else
           return c;
         }
  double  calculation_perimetr()
        {
        per=a+b+c;
        return per;
        }
 
  double  calculation_a_corner()
        {
        alpha=rad1=acos(((b*b)+c*c-a*a)/(2*c*b));
        gr1=rad1*180/3.14;
        cout<<"\nALPHA size is: \n"<<gr1<<endl<<endl;
        return alpha, gr1, rad1;
        }
  double calculation_b_corner()
        {
        betta=rad2=acos(((a*a)+c*c-b*b)/(2*c*a));
        gr2=rad2*180/3.14;
        cout<<"BETTA size is: \n"<<gr2<<endl<<endl;
         return betta, gr2, rad2;
        }
  double calculation_c_corner()
        {
        gamma=rad3=acos(((b*b)+a*a-c*c)/(2*a*b));
        gr3=rad3*180/3.14;
         cout<<"GAMMA size is: \n"<<gr3<<endl<<endl;
         return gamma, gr3, rad3;
        }
void GET(){cout<<a<<"\n"<<b<<"\n"<<c<<"\n\n\n"<<per<<"\n\n"<<gr1<<"\n"<<gr2<<"\n"<<gr3<<"\n\n";}
};
 
class Equiteral: Triangle {
public:
   Equiteral();
   Equiteral(double x);
  ~Equiteral();
 
  double  change_a()
        {cout<<"\n\nInsert new a: "<<endl;
         cin>>a;
       if (a<0)
           {
           cout<<"Error!!!";
           cout<<"Insert new a: "<<endl;
        cin>>a;
           return a;
            }
         else
         return a;
        }
  double change_b()
        {cout<<"Insert new b: "<<endl;
         cin>>b;
         if (b<0 || b!=a)
           {
            cout<<"Error!!! Chislo b dolzhno ravnyaztsya a!";
            cout<<"Insert new b: "<<endl;
            cin>>b;
           return b;
           }
         else
          return b;
        }
  double change_c()
        {cout<<"Insert new b: "<<endl;
         cin>>c;
        if (c<0 || c!=a || c!=b)
           {
            cout<<"Error!!! Chislo c dolzhno ravnyaztsya a i b!";
            cout<<"Insert new c: "<<endl;
            cin>>c;
            return c;
           }
         else
          return c;
        }
   double  calculation_square()
        {
        Sq=0.5*b*sqrt(b*b-(b/2.0)*(b/2.0));
        return Sq;
        }
 
   double  calculation_a_corner()
        {
        alpha=rad1=acos(((b*b)+c*c-a*a)/(2*c*b));
        gr1=rad1*180/3.14;
        cout<<"\nALPHA size is: \n"<<gr1<<endl<<endl;
        return alpha, gr1, rad1;
        }
  double calculation_b_corner()
        {
        betta=rad2=acos(((a*a)+c*c-b*b)/(2*c*a));
        gr2=rad2*180/3.14;
        cout<<"BETTA size is: \n"<<gr2<<endl<<endl;
         return betta, gr2, rad2;
        }
  double calculation_c_corner()
        {
        gamma=rad3=acos(((b*b)+a*a-c*c)/(2*a*b));
        gr3=rad3*180/3.14;
         cout<<"GAMMA size is: \n"<<gr3<<endl<<endl;
         return gamma, gr3, rad3;
         }
 
void GET(){cout<<a<<"\n"<<b<<"\n"<<c<<"\n\n\n"<<Sq<<"\n\n"<<gr1<<"\n"<<gr2<<"\n"<<gr3<<"\n\n";}
        double x;
};
 
//constructor Triangle
Triangle::Triangle():a(5), b(6), c(7){};
Triangle::~Triangle() {};
 
 
//constructor Equiteral
Equiteral::Equiteral(){};
Equiteral::Equiteral(double x){change_a();change_b();change_c();calculation_a_corner();calculation_b_corner();calculation_c_corner();calculation_square();}
Equiteral::~Equiteral(){};
 
 
 int  main ()
   {
    Triangle TR1;
    TR1.vvod_a();
    TR1.vvod_b();
    TR1.vvod_c();
    TR1.calculation_perimetr();
    TR1.calculation_a_corner();
    TR1.calculation_b_corner();
    TR1.calculation_c_corner();
    TR1.GET();
 
    Equiteral EQ1(1);
    EQ1.GET();
     getch();
     return 0;
   }