int main(int argc, const char * argv[])
{
int kase;cin >> kase;
while(kase--) {
double x, y, c;cin >> x >> y >> c;
double l = 0, r = min(x, y);
Rep(i, 1, 100) {
double mid = (l + r) / 2.0;
double angle1 = acos(mid / x);
double angle2 = acos(mid / y);
double t = c / tan(angle1) + c / tan(angle2);
if (t < mid) l = mid;
else r = mid;
}
printf("Case %d: %.12lf\n", ++nCase, l);
}
return 0;
}