#include<bits/stdc++.h>
using namespace std;
int main(){

	double hi,lo,mid,x,y,c,h,ans;
	int t,i,j,k,n;
	scanf("%d",&t);
	for(i=1;i<=t;i++){
		scanf("%lf %lf %lf",&x,&y,&c);
		lo=0.0;
		hi=min(x,y);
		while(lo+1e-7<hi){
			mid=(lo+hi)/2.0;
			h=sqrt(x*x-mid*mid)*sqrt(y*y-mid*mid)/(sqrt(x*x-mid*mid)+sqrt(y*y-mid*mid));
			if(h-c>1e-7)lo=mid;
			else hi=mid;
		}
		printf("Case %d: %.10lf\n",i,lo);
	}






}