trapezi

#include<stdio.h>
#include<math.h>
#include<stdlib.h>

struct Tacka {
  double x,y;
};
struct Trapez {
  struct Tacka A,B,C,D;
};

double pitagora(struct Tacka A, struct Tacka B){
  return sqrt((A.x-B.x)*(A.x-B.x)+(A.y-B.y)*(A.y-B.y));
}


double povrsina_trokuta(struct Tacka A, struct Tacka B, struct Tacka C){
  return fabs(A.x*(B.y-C.y)+B.x*(C.y-A.y)+C.x*(A.y-B.y))/2.;
}

double visina_trapez(struct Trapez trapez){
  return (2.*povrsina_trokuta(trapez.A,trapez.B,trapez.D))/pitagora(trapez.A,trapez.B);
}

double povrsina_trapeza(struct Trapez trapez){
  return (pitagora(trapez.A,trapez.B)+pitagora(trapez.D,trapez.C))*visina_trapez(trapez)/2.;
}

double obim_trapez(struct Trapez trapez){
  return pitagora(trapez.A,trapez.B)+pitagora(trapez.A,trapez.D)+pitagora(trapez.C,trapez.B)+pitagora(trapez.C,trapez.D);
}

void trapezi(struct Trapez *niz, int vel, double *obim, double *povrsina){
  int i;
  for(i=0;i<vel;i++){
    obim[i]=obim_trapez(niz[i]);
    povrsina[i]=povrsina_trapeza(niz[i]);
  }
}

int main(){
  /* AT9: Rotacije */
  struct Trapez niz[] = {
    { {-4,2}, {0.950, 6.950}, {-2.586, 7.657}, {-5.414, 4.828} }, // 45 stepeni
    { {-4,2}, {-7.5, 8.062}, {-9.098, 4.830}, {-7.098, 1.366} }, // 120 stepeni
    { {-4,2}, {-11, 2}, {-9, -1}, {-5, -1} }, // 180 stepeni
    { {-4,2}, {-4, -5}, {-1, -3}, {-1, 1} } // 270 stepeni
  };
  double obimi[4], povrsine[4];
  int i;

  trapezi(niz, 4, obimi, povrsine);
  for (i=0; i<4; i++)
    printf("%.2f ", obimi[i]);
}