#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, x, y;
  double r, v, d;
  cin >> n >> r >> v;
  double cir = 2 * r * 3.141592653589793238462643383279502884L;
  while (n--) {
    cin >> x >> y;
    d = y - x;
    int rot = (int)(d / cir);
    double rtn = rot * (cir / v);
    d -= rot * cir;
    double s = -(3.141592653589793238462643383279502884L) / 2;
    double e = 3.141592653589793238462643383279502884L / 2;
    double m = (s + e) / 2;
    double target = 3.141592653589793238462643383279502884L / 2 - d / 2 / r;
    int iter = 0;
    while (true) {
      iter++;
      double err = m - cos(m) - target;
      if (((err) > 0 ? (err) : (-(err))) < 0.00000000000000000001L ||
          iter > 80) {
        break;
      } else if (err > 0) {
        e = m;
      } else {
        s = m;
      }
      m = (s + e) / 2;
    }
    rtn += 2 * (3.141592653589793238462643383279502884L / 2 - m) * r / v;
    printf("%.12f\n", rtn);
  }
}
