#include <bits/stdc++.h>
using namespace std;
pair<double, double> operator+(pair<double, double> A, pair<double, double> B) {
  return make_pair(A.first + B.first, A.second + B.second);
}
pair<double, double> operator-(pair<double, double> A, pair<double, double> B) {
  return make_pair(A.first - B.first, A.second - B.second);
}
pair<double, double> operator*(pair<double, double> A, double k) {
  return make_pair(A.first * k, A.second * k);
}
double vmax, T;
pair<double, double> s, t, v, w;
int cnt = 0;
void init() {
  cin >> s.first >> s.second >> t.first >> t.second;
  cin >> vmax >> T;
  cin >> v.first >> v.second;
  cin >> w.first >> w.second;
  double l = 0, r = 1e9, ans = 0;
  while (cnt <= 1000000) {
    cnt++;
    double mid = (l + r) * 0.5;
    pair<double, double> st = s;
    if (mid <= T)
      st = st + v * mid;
    else
      st = st + v * T + w * (mid - T);
    double now = (sqrt(((t.first - st.first) * (t.first - st.first)) +
                       ((t.second - st.second) * (t.second - st.second))));
    if (now / vmax <= mid) {
      ans = mid;
      r = mid;
    } else
      l = mid;
  }
  printf("%.10lf", ans);
  return;
}
int main() {
  init();
  return 0;
}
