#include<bits/stdc++.h>
using namespace std;
#define eps 1e-6

int main()
{
    double x,y,c,h1,h2,h,mid,lo,hi;
    int t,i,j,cas;
    cin>>t;
    for(cas=1;cas<=t;cas++)
    {
        cin>>x>>y>>c;
        lo=0;
        hi=min(x,y);
      //  cout<<"hi "<<hi<<endl;


        j=100;
        while((hi-lo)>=eps)
        {
            mid=(lo+hi)/2.00;
            h1=sqrt((x*x)-(mid*mid));
            h2=sqrt((y*y)-(mid*mid));
            h=(h1*h2)/(h1+h2);
            if(h<=c)
                hi=mid;
            else
                lo=mid;
        }
        cout<<"Case "<<cas<<": "<<setprecision(10)<<mid<<endl;
    }
    return 0;
}