#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:1677721600")
using namespace std;
const double EPS = 1E-9;
int main() {
  int n, r, vv;
  cin >> n >> r >> vv;
  for (int k = 0; k < (int)n; k++) {
    int s, f;
    cin >> s >> f;
    double dist = (1.0 * f - s) / r;
    int full = (int)(dist / 2 / 3.1415926535897932384626433);
    double angle = dist - full * 2 * 3.1415926535897932384626433;
    double low = 0;
    double high = 3.1415926535897932384626433;
    while (low * r / vv < (high - EPS) * r / vv &&
           (low + low) * r * EPS / vv < high * r / vv) {
      double mid = (high + low) / 2;
      double now = 2 * (mid + sin(mid));
      if (now < angle)
        low = mid;
      else
        high = mid;
    }
    if (angle < 1E-7) {
      low = angle / 4;
    }
    double fullangle = 2 * low + full * 2 * 3.1415926535897932384626433;
    double time = fullangle * r / vv;
    cout << fixed << setprecision(8) << time << endl;
  }
  return 0;
}
