#include <bits/stdc++.h>
using namespace std;
const long double pi = acos(-1);
const int INF = 0x3f3f3f3f;
const long long LINF = 0x3f3f3f3f3f3f3f3fll;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int n;
  long double R, v;
  cin >> n >> R >> v;
  cout << fixed << setprecision(12);
  while (n--) {
    long double ss, ff;
    cin >> ss >> ff;
    long double D = (ff - ss) / 2;
    auto solve = [&](long double theta_s) {
      long double l = 0, r = 1e9;
      for (int i = 0; i < 100; i++) {
        long double m = (l + r) / 2;
        R*(m - sinl(m + theta_s)) > D ? r = m : l = m;
      }
      return (R * (l + r) / 2) / v * 2;
    };
    cout << min(solve(0), solve(pi)) << '\n';
  }
  return 0;
}
