1 #include <cstdio> 2 #include <cmath> 3  4 #define exp 1e-9 5  6 const double PI = acos(-1.0); 7  8 int main() { 9     int t;10     double r, R, H, v, lf, rt, mid, r0, nv;11     scanf("%d", &t);12 13     while (t--) {14         scanf("%lf%lf%lf%lf", &r, &R, &H, &v);15         lf = 0;16         rt = H;17         while (rt >= lf+exp) {18             mid = (lf+rt)/2;19             r0 = mid*(R-r)/H+r;20             nv = PI*(r*r+r*r0+r0*r0)*mid/3;21             if (fabs(nv -v) <= exp)22                 break;23             if (nv < v)24                 lf = mid;25             else26                 rt = mid;27         }28         printf("%.6lf\n", mid);29     }30 31     return 0;32 }