ZOJ 2559 The Smart Bomb

题意：给定你三个圆心，三个圆相交，求每个圆心大小

解题代码：由于任意两个圆的半径和为其圆心的连线的长度，可以列出三个二元一次方程，求解可得　　

解题代码：

#include <stdio.h>
    #include <string.h>
    #include <stdlib.h>
    #include <math.h>
    double distance(double x1,double y1,double x2,double y2)
    {
      return  sqrt((x1-x2)*(x1-x2) + (y1-y2)*(y1-y2));
    }
    int main()
    {
       double x1,x2,x3,y1,y2,y3;
       while(scanf("%lf %lf %lf %lf %lf %lf",&x1,&y1,&x2,&y2,&x3,&y3) != EOF)
       {
          double d1 = distance(x1,y1,x2,y2);
          double d2 = distance(x1,y1,x3,y3);
          double d3 = distance(x2,y2,x3,y3);
          double a,b,c;
          a = (d1+d3-d2)*1.0/2;
          b = (d2+d3-d1)*1.0/2;
          c = (d1+d2-d3)*1.0/2;
          printf("%lf\n%lf\n%lf\n",c,a,b);

       }
     return 0 ;
    }