//Tao class diem

#include<conio.h>

#include<stdio.h>

#include<iostream.h>

#include<math.h>

//-------------

class diem

{

      private:

              double hd,td;

      public:

             diem();

             diem(double x,double y);

             void nhap();

             void in();

             friend double dist(diem da, diem db);

};

//-------------

class tamgiac

{

      private:

              diem d1,d2,d3;

      public:

             tamgiac();

             tamgiac(double xa,double ya,double xb,double yb,double ca,double yc);

             void nhap();

             void in();

             friend double cv(tamgiac tg);

             friend double dt(tamgiac tg);

};

//-------------

diem::diem()

{hd=0;td=0;}

//-------------

{hd=x;td=y;}

//-----------

void diem::nhap()

{

     cout<<"

HD: ";cin>>hd;

     cout<<"

TD: ";cin>>td;

}

//------------

void diem::in()

{

     cout<<"( "<<hd<<","<<td<<" )";

}

//--------------

double dist(diem da, diem db)

{

       double x,xa,xb,ya,yb;

       xa=da.hd;

       ya=da.td;

       xb=db.hd;

       yb=db.td;

       x=sqrt(((xb-xa)*(xb-xa))+(yb-ya)*(yb-ya));

       return x;

}

//-------------

tamgiac::tamgiac()

{

   d1=diem(0,0);

   d2=diem(0,0);

   d3=diem(0,0);

}

//------------

tamgiac::tamgiac(double xa,double ya,double xb,double yb,double xc,double yc)

{

   d1=diem(xa,ya);

   d2=diem(xb,yb);

   d3=diem(xc,yc);

}

//------------

void tamgiac::nhap()

{

     cout<<"

Nhap 3 dinh cua tam giac!";

     cout<<"

Dinh 1: ";d1.nhap();

     cout<<"

Dinh 2: ";d2.nhap();

     cout<<"

Dinh 3: ";d3.nhap();

}

//------------

void tamgiac::in()

{

     cout<<"

Tam giac co 3 dinh la: ";

     d1.in();cout<<" ";d2.in();cout<<" ";d3.in();

}

//-----------

double cv(tamgiac tg)

{

       double a=dist(tg.d1,tg.d2);

       double b=dist(tg.d2,tg.d3);

       double c=dist(tg.d3,tg.d1);

       return (a+b+c);

}

//-------------

double dt(tamgiac tg)

{

       double p=cv(tg)/2;

       double a=(p-dist(tg.d1,tg.d2));

       double b=(p-dist(tg.d2,tg.d3));

       double c=(p-dist(tg.d3,tg.d1));

       return(p*a*b*c);

}

//------------

int main()

{

    tamgiac tg;

    tg.nhap();

    tg.in();

    cout<<"

C: "<<cv(tg);

    cout<<"

S: "<<dt(tg);

    getch();

}