Вычислить площадь треугольников с помощью формулы Герона

#include <iostream>
#include <cmath>
 
using namespace std;
 
float area(float S, float s);
 
int main(){
    float S, A, B, C, a, b, c, s;
    
    cout << "Area this is triangle = " << area(S, s);
    
    return 0;
}
 
float area(float S, float s){
    int A, B, C, a, b, c;
    int Ax = 1, Ay = 1, Bx = 4, By = 2, Cx = 2, Cy = 3.5;
    int ax = 1, ay = 2, bx = 4, by = 1, cx = 3, cy = 3.5;
    double p, p1;
    
    if ((A < B + C) && (B < A + C) && (C < A + B))
        cout << "First triangle exsits" << endl;
    else
        cout << "First triangle doesn't exists" << endl;
 
    if((a < b + c) && (b < a + c) && (c < a + b))
        cout << "Second triangle exsits" << endl;
    else
        cout << "Second triangle doesn't exsits" << endl;
    
    A = abs(sqrt(pow((Bx - Ax),2) + (pow((By - Ay),2))));
    B = abs(sqrt(pow((Cx - Bx),2) + (pow((Cy - By),2))));
    C = abs(sqrt(pow((Ax - Cx),2) + (pow((Ay - Cy),2))));
    
    a = abs(sqrt(pow((bx - ax),2) + (pow((by - ay),2))));
    b = abs(sqrt(pow((cx - bx),2) + (pow((cy - by),2))));
    c = abs(sqrt(pow((ax - cx),2) + (pow((ay - cy),2))));
    
    p = (A + B + C) / 2;
    p1 = (a + b + c) / 2;
    
    S = sqrt(p * (p - A) * (p - B) * (p - C));
    s = sqrt(p * (p - a) * (p - b) * (p - c));
    
    cout << "Area first triangle: " << S << endl;
    cout << "Area second triangle: " << s << endl;
    
    if(S > s){
        cout << "The area of the first triangle is larger than the second" << endl;
    }
    else if(S < s){
        cout << "The area of the second triangle is larger than the first" << endl;
    }
    else{
        cout << "The area of the triangles are equal" << endl;
    }
    return S, s;
}

#include <iostream>
#include <cmath>
 
using namespace std;
 
double TriangleArea(double x1, double y1, double x2, double y2, double x3, double y3)
{   
    double a, b, c, p, eps=1e-9;
    a=fabs(sqrt(pow(x1-x2,2)+pow(y1-y2,2))); // или a=hypot(x1-x2,y1-y2); 
    b=fabs(sqrt(pow(x2-x3,2)+pow(y2-y3,2))); // или b=hypot(x2-x3,y2-y3);
    c=fabs(sqrt(pow(x1-x3,2)+pow(y1-y3,2))); // или c=hypot(x1-x3,y1-y3);
    
    if (a<b+c-eps && b<a+c-eps && c<a+b-eps)
    {
        p=(a+b+c)/2.;
        return sqrt(p*(p-a)*(p-b)*(p-c));
    }
    return 0;   
}
 
int main()
{
    
    double A1x=1., A1y=1., B1x=4., B1y=2., C1x=2., C1y=3.5, S1, eps=1e-9;
    double A2x=1., A2y=2., B2x=4., B2y=1., C2x=3., C2y=3.5, S2;
    
    S1=TriangleArea(A1x,A1y,B1x,B1y,C1x,C1y);
    if (S1<=eps) cout << "First triangle doesn't exist\n";
    else cout << "Area 1 = " << S1 << "\n";
    
    S2=TriangleArea(A2x,A2y,B2x,B2y,C2x,C2y);
    if (S2<=eps) cout << "Second triangle doesn't exist\n"; 
    else cout << "Area 2 = " << S2 << "\n";
    
    if(S1>eps && S2>eps)
    {
        if(S1>S2+eps) cout << "Area 1 > Area 2\n";
        else if (S1<S2-eps) cout << "Area 1 <  Area 2\n";
        else cout << "Area 1 = Area 2\n";
    }
  
system("pause");
return 0;
}

double a=4.3, b=4.3;
if (a==b) cout << "YES\n";
else cout << "NO\n";