#include <bits/stdc++.h>
const int oo = 0x3f3f3f3f;
const long double EPS = 1e-7;
std::pair<long double, long double> S, T;
long double vmax, t0;
std::pair<long double, long double> v, w;
inline long double dist(const std::pair<long double, long double> &a,
                        const std::pair<long double, long double> &b) {
  return sqrt((a.first - b.first) * (a.first - b.first) +
              (a.second - b.second) * (a.second - b.second));
}
bool check(long double t) {
  std::pair<long double, long double> T0 = T;
  if (t <= t0) {
    T0.first -= t * v.first;
    T0.second -= t * v.second;
  } else {
    T0.first -= t0 * v.first + (t - t0) * w.first;
    T0.second -= t0 * v.second + (t - t0) * w.second;
  }
  return dist(S, T0) / vmax <= t;
}
int main() {
  std::cin >> S.first >> S.second >> T.first >> T.second >> vmax >> t0 >>
      v.first >> v.second >> w.first >> w.second;
  long double l = 0, r = 1e30;
  while (l + EPS < r) {
    long double mid = (l + r) / 2;
    if (check(mid))
      r = mid;
    else
      l = mid;
  }
  std::cout << std::setprecision(20) << l << std::endl;
  return 0;
}
