Area of parralelogram

#include<stdio.h>
int main()
{
    int i,dx,dy,area;
    double ax,ay,bx,by,cx,cy,x,y,t;
    scanf("%lf",&t);


    for(i=1;i<=t;i++){

    scanf("%lf %lf %lf %lf %lf %lf",&ax,&ay,&bx,&by,&cx,&cy);

    x=(ax+cx)/2;
    y=(ay+cy)/2;

    dx=(2*x)-bx;
    dy=(2*y)-by;

    area=.5*( (ax*by+bx*cy+cx*dy+dx*ay)-(ay*bx+by*cx+cy*dx+dy*ax) );

    if(area<0){area=area*-1; }


    printf("Case %d: %d %d %d\n",i,dx,dy,area);


    }
}