Date su 4 tacke. Izracunati P cetvorougla (voditi racuna da li su tacke kolinearne ili ne).
Pomoc: Koristiti funkciju "duzina duzi".
A(x1,y1), B(x2,y2), C(x3,y3), D(x4,y4).

#include <iostream>
#include <cmath>
#include <cstdlib>
 
using namespace std;
 
float duzinaStrane (float a, float b, float c, float d)
{
        return sqrt(pow(a-c,2) + pow(b-d,2));
}
 
float povrsina (float a, float b, float c)
{
    float s = (a+b+c)*0.5;
    float d = (s*(s-a)*(s-b)*(s-c));
    return d;
}
 
int main()
{
    float x1,y1,x2,y2,x3,y3,x4,y4, min, ab, bc, cd, ad, ac, obim, pov;
    cout<<"Unesite koordinate tacke A: "<<endl;
    cin>>x1>>y1;
    cout<<"Unesite koordinate tacke B: "<<endl;
    cin>>x2>>y2;
    cout<<"Unesite koordinate tacke C: "<<endl;
    cin>>x3>>y3;
    cout<<"Unesite koordinate tacke D: "<<endl;
    cin>>x4>>y4;
 
    ab = duzinaStrane(x1,y1,x2,y2);
    bc = duzinaStrane(x2,y2,x3,y3);
    cd = duzinaStrane(x3,y3,x4,y4);
    ad = duzinaStrane(x1,y1,x4,y4);
    ac = sqrt(pow (x1-x3,2) + pow ((y1-y3),2));
 
    pov = povrsina(ad,ac,cd) + povrsina(ab, bc, ac);
    obim = ab+bc+cd+ad;
 
    cout<<"Obim je: " << obim<<endl;
    cout<<"Povrsina je: "<< povrsina<<endl;
    system("pause");
    return 0;
}