1 #include <cstdio>
 2 #include <cmath>
 3 
 4 const double PI = acos(-1.0);
 5 int T;
 6 double r,R,H,V;
 7 
 8 int main()
 9 {
10     scanf("%d", &T);
11     while(T--){
12         scanf("%lf%lf%lf%lf", &r, &R, &H, &V);
13         double low = 0, high = H;
14         double mid;
15         while(high-low>1e-8){
16             mid = (low+high)/2;
17             double mid_r = mid/H*(R-r)+r;
18             double mid_v = PI/3*mid*(r*r+r*mid_r+mid_r*mid_r);
19             if(mid_v<V)
20                 low = mid+1e-8;
21             else
22                 high = mid-1e-8;
23         }
24         mid = (low+high)/2;
25         printf("%.6f\n", mid);
26     }
27     return 0;
28 }