#include<iostream>
#include<math.h>
using namespace std;

void YuanXin(double x1,double y1,double x2,double y2,double R,double &x,double &y)
{
	double c1 = (x2*x2 - x1*x1 + y2*y2 - y1*y1) / (2 *(x2 - x1));
	double c2 = (y2 - y1) / (x2 - x1);
	double A = (c2*c2 + 1);
	double B = (2 * x1*c2 - 2 * c1*c2 - 2 * y1);
	double C = x1*x1 - 2 * x1*c1 + c1*c1 + y1*y1 - R*R;
	cout << B*B - 4 * A*C << endl;
	y = (-B + sqrt(B*B - 4 * A*C)) / (2 * A);
	x = c1 - c2 * y;
	cout << "x=" << x << "y=" << y << endl;
}

int main()
{ 
	double a=0, b=0;
	YuanXin(1, -6, 6, -1, 5, a, b);
	cout << "a=" << a << "b=" << b << endl;
	return 0;
}