Poj Solution 1905

http://poj.org/problem?id=1905

/* @author: */
import java.util.Scanner;
public class Main{
  static final  double PI=3.1415926;
  static final  double eps=1e-6;

  public static void main(String args[])
{    
  Scanner sc=new Scanner(System.in);
  double L,n,C,M,y1,low,high,mid;
  while(true)
  {
     L=sc.nextDouble();
     n=sc.nextDouble();
     C=sc.nextDouble();
     if(L==-1&&n==-1&&C==-1)break;
     if(L<=eps||n<=eps||C<=eps)
    {
      System.out.println("0.000");
      continue;
    }
     M=(1+n*C)*L;
     low=0;
     high=PI;
     while(true)
     {
    mid=(low+high)/2;
    y1=M-L*mid/Math.sin(mid);
    if(Math.abs(y1)<=eps)break;
    else if(y1>0)low=mid;
    else high=mid;
     }
     System.out.printf("%.3fn",L*Math.tan(mid/2)/2);
    }
  }
}