UVA190 Circle Through Three Points

#include<iostream>
#include<cmath>
#include<cstdio>
using namespace std;

double ax,ay,bx,by,cx,cy,x,y,a,b,c,p,r,f;
double A1,B1,A2,B2,C1,C2;

int main()
{
    while(cin>>ax>>ay>>bx>>by>>cx>>cy){
        a=pow((ax-bx)*(ax-bx)+(ay-by)*(ay-by),0.5);
		b=pow((ax-cx)*(ax-cx)+(ay-cy)*(ay-cy),0.5);
		c=pow((bx-cx)*(bx-cx)+(by-cy)*(by-cy),0.5);
		p=(a+b+c)*0.5;
		r=(a*b*c)/(4*pow(p*(p-a)*(p-b)*(p-c),0.5));

		A1=2*(bx-ax);
		B1=2*(by-ay);
		C1=bx*bx+by*by-ax*ax-ay*ay;
		A2=2*(cx-bx);
		B2=2*(cy-by);
		C2=cx*cx+cy*cy-bx*bx-by*by;
		x=((C1*B2)-(C2*B1))/((A1*B2)-(A2*B1));
		y=((A1*C2)-(A2*C1))/((A1*B2)-(A2*B1));

		f=r*r-x*x-y*y;

		cout << "(x " << (x>0?"- ":"+ ");
		printf("%.3f)^2 + (y ",abs(x));
		cout << (y>0?"- ":"+ ");
		printf("%.3f)^2 = %.3f^2\n",abs(y),r);

		cout << "x^2 + y^2 " << (x>0?"- ":"+ ");
		printf("%.3fx ",2*abs(x));
		cout << (y>0?"- ":"+ ");
		printf("%.3fy ",2*abs(y));
		cout << (f>0?"- ":"+ ");
		printf("%.3f = 0\n\n",abs(f));
    }
    return 0;
}