Треугольник задан координатами вершин. Найти его периметр и площадь

#include <iostream.h>
#include <conio.h>              
#include <stdio.h>
#include <math.h>
int main()
{
int x1, x2, y1, y2, z1, z2;
double AB,BC,AC, ab, bc, ac, p,s,S;
cout<<" Vvedite x1="; cin>>x1;
cout<<" Vvedite x2="; cin>>x2;
cout<<" Vvedite y1="; cin>>y1;
cout<<" vvedite y2="; cin>>y2;
cout<<" Vvedite z1="; cin>>z1;
cout<<" Vvedite z2="; cin>>z2;
AB=((x1-y1)*(x1-y1)+(x2-y2)*(x2-y2)); 
ab= sqrt(AB);
BC=((x1-z1)*(x1-z1)+(x2-z2)*(x2-z2)); 
bc= sqrt(BC);
AC=((y1-z1)*(y1-z1)+(y2-z2)*(y2-z2)); 
ac= sqrt(AC);
p=((ab+bc+ac)/2);
S=((p-AB)*(p-BC)*(p-BC)*p);
s= sqrt(S);
cout<<"S=" <<s<< endl;
return 0;
}

#include <iostream>
#include <conio.h>              
#include <stdio.h>
#include <math.h>
using namespace std;
int main()
{
    int x1, x2, y1, y2, z1, z2;
    double AB,BC,AC, ab, bc, ac, p,s,S;
    cout<<" Vvedite x1="; cin>>x1;
    cout<<" Vvedite x2="; cin>>x2;
    cout<<" Vvedite y1="; cin>>y1;
    cout<<" vvedite y2="; cin>>y2;
    cout<<" Vvedite z1="; cin>>z1;
    cout<<" Vvedite z2="; cin>>z2;
    AB=((x1-y1)*(x1-y1)+(x2-y2)*(x2-y2)); 
    ab= sqrt(AB);
    BC=((x1-z1)*(x1-z1)+(x2-z2)*(x2-z2)); 
    bc= sqrt(BC);
    AC=((y1-z1)*(y1-z1)+(y2-z2)*(y2-z2)); 
    ac= sqrt(AC);
    p=((ab+bc+ac)/2);
    S=((p-ab)*(p-bc)*(p-bc)*p);
    s= sqrt(S);
    cout<<"S=" <<s<< endl;
    system("pause");
    return 0;
}