点关于直线的对称点

#include 
 int main()
{
    int n;
    float a,b,A,B,C,a1,b1;
    scanf("%d\n",&n);
    while(n--)
    {  scanf("%f %f %f %f %f",&a,&b,&A,&B,&C);
     int a1=int (a-2*A*(A*a+B*b+C)/(A*A+B*B));
     int b1=int (b-2*B*(A*a+B*b+C)/(A*A+B*B));
     printf("%d %d\n",a1,b1);
    }
}

Ax+By+C=0

double dist(POINT p1,POINT p2)                // 返回两点之间欧氏距离 
{ 
return( sqrt( (p1.x-p2.x)*(p1.x-p2.x)+(p1.y-p2.y)*(p1.y-p2.y) ) ); 
}