#include <bits/stdc++.h>
using namespace std;
double dist(double x1, double y1, double x2, double y2) {
  return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}
int main() {
  double xs, ys, yf, xf;
  cin >> xs >> ys >> xf >> yf;
  double vmax, t_change;
  cin >> vmax >> t_change;
  double time[3] = {0, t_change, 1e9};
  double xx[2];
  double yy[2];
  for (int i = 0; i < 2; i++) {
    cin >> xx[i] >> yy[i];
  }
  double left = 0;
  double right = 1e9;
  for (int iter = 0; iter < 100; ++iter) {
    double mid = (left + right) / 2.;
    double x_cur = xs;
    double y_cur = ys;
    for (int i = 0; i < 2; i++) {
      if (time[i] < mid) {
        double dur = min(time[i + 1], mid) - time[i];
        x_cur += dur * xx[i];
        y_cur += dur * yy[i];
      }
    }
    double len = dist(x_cur, y_cur, xf, yf);
    double my_time = len / vmax;
    if (my_time < mid)
      right = mid;
    else
      left = mid;
  }
  cout.precision(10);
  cout << (double)(left);
  return 0;
}
