#include <bits/stdc++.h>
using namespace std;
const double PI = 4 * atan(1.);
const int IT = 200;
int n;
double R, v;
double solve() {
  double w = v / R;
  double l, r;
  scanf("%lf%lf", &l, &r);
  double L = r - l;
  int z = (int)(L / (2 * PI * R));
  L -= z * (2 * PI * R);
  L /= 2;
  l = 0, r = PI * R / v;
  for (int it = 0; it < IT; it++) {
    double t = (l + r) / 2;
    double dL = R * (PI - w * t + sin(w * t));
    if (dL > L)
      l = t;
    else
      r = t;
  }
  double t1 = l;
  double t2 = 2 * PI * R / v - t1;
  double LL = v * (t2 - t1);
  return (LL + z * 2 * PI * R) / v;
}
int main() {
  scanf("%d%lf%lf", &n, &R, &v);
  while (n--) printf("%.12lf\n", solve());
  return 0;
}
