#define MAX(a,b) ((a)>(b)?(a):(b))
#define MIN(a,b) ((a)<(b)?(a):(b))
#define filer() freopen("in.txt","r",stdin)
#define filew() freopen("out.txt","w",stdout)
#define SET(a, x) memset((a), (x), sizeof(a))
#define ll long long
#include<iostream>
#include<stdio.h>
#include<string.h>
#include<math.h>
#include<algorithm>
#include<queue>
#include<stack>
#include<vector>

using namespace std;






int main()
{
    //filer();
    double L,n,C,arc,hi,lo,mid,r2,r1,d,a;
    int T,cas=0;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%lf%lf%lf",&L,&n,&C);
        if(L<0 && n<0 &&C<0)break;
        arc=(1+(n*C))*L;
        //printf("%lf\n",arc);
        hi=(acos(-1)/2.00);
        //printf("%lf\n",hi);
        lo=1e-9;

        while(fabs(hi-lo)>1e-9)
        {
            mid=(hi+lo)/2.0;
            r1=arc/(2.0*mid);
            r2=L/(2*sin(mid));


            //printf("%lf %lf %lf %lf\n",r1,r2,mid,fabs(r1-r2));
            if(fabs(r1-r2)<1e-7)
            {
                a=r2-(r2*cos(mid));
                printf("Case %d: %.6lf\n",++cas,a);
                break;
            }
            else if(r1>r2)lo=mid+1e-7;
            else hi=mid-1e-7;
        }
    }


    return 0;
}