#include <bits/stdc++.h>
using namespace std;
int main() {
  double x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  double vmax, t0, vx, vy, wx, wy;
  cin >> vmax >> t0 >> vx >> vy >> wx >> wy;
  double dx = (x2 - x1);
  double dy = (y2 - y1);
  double l = 0, r = 1e16;
  double ans = 1e16;
  for (int i = 0; i < 200; i++) {
    double t = (l + r) / 2;
    double xx = vx * (t0 < t ? t0 : t);
    double yy = vy * (t0 < t ? t0 : t);
    if (t > t0) {
      xx += wx * (t - t0);
      yy += wy * (t - t0);
    }
    if ((xx - dx) * (xx - dx) + (yy - dy) * (yy - dy) > vmax * vmax * t * t)
      l = t;
    else {
      r = t;
      ans = t;
    }
  }
  printf("%.12f\n", ans);
}
