#include <bits/stdc++.h>
using namespace std;
inline void read_string_to_vector(vector<string> &vec) {
  string str;
  getline(cin, str);
  vec.push_back(str);
}
template <typename T>
inline void read_digit_to_vector(vector<T> &vec) {
  T t;
  cin >> t;
  vec.push_back(t);
}
template <typename T>
inline T gcd(T a, T b) {
  return b ? gcd(b, a % b) : a;
}
pair<long long, long long> v0, v1;
pair<long long, long long> v, w;
long long vm, t;
bool mf(double time) {
  double x =
      v0.first + v.first * min((double)t, time) + w.first * max(0.0, time - t);
  double y = v0.second + v.second * min((double)t, time) +
             w.second * max(0.0, time - t);
  double md = sqrt((v1.first - x) * (v1.first - x) +
                   (v1.second - y) * (v1.second - y)) /
              vm;
  return time >= md;
}
double bs(void) {
  double l = 0.0f, r = 1e14 + 10;
  double md;
  while (r - l > 1e-6) {
    md = (l + r) * 0.5;
    if (!mf(md))
      l = md;
    else
      r = md;
  }
  return r;
}
int main() {
  ios::sync_with_stdio(false);
  cin >> v0.first >> v0.second >> v1.first >> v1.second;
  cin >> vm >> t;
  cin >> v.first >> v.second >> w.first >> w.second;
  printf("%.8llf\n", bs());
  return 0;
}
