#include <bits/stdc++.h>
using namespace std;
const double inf = 1e9 + 1, eps = 1e-7;
pair<double, double> st, ed, v, w;
double vmax, t;
double len(const pair<double, double>& p) {
  return sqrt(p.first * p.first + p.second * p.second);
}
bool check(double ti) {
  double x = st.first, y = st.second;
  x += v.first * min(ti, t);
  y += v.second * min(ti, t);
  x += w.first * max(ti - t, 0.0);
  y += w.second * max(ti - t, 0.0);
  pair<double, double> dir = make_pair(ed.first - x, ed.second - y);
  return len(dir) <= ti * vmax;
}
double bs(double l, double r) {
  if (r - l < eps) return l;
  double m = (l + r) / 2.0;
  if (check(m)) return bs(l, m);
  return bs(m, r);
}
int main() {
  cin >> st.first >> st.second >> ed.first >> ed.second;
  cin >> vmax >> t;
  cin >> v.first >> v.second >> w.first >> w.second;
  cout << fixed << setprecision(20) << bs(0, inf);
  return 0;
}
