#include <bits/stdc++.h>
using namespace std;
const int N = 3e5 + 2;
complex<long double> a, b, v, w;
long double v_max, t;
bool check(long double T) {
  complex<long double> res = a + min(t, T) * v + max((long double)0, T - t) * w;
  return hypot(((b) - (res)).real(), ((b) - (res)).imag()) / (long double)T <=
         v_max;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cout << setprecision(6) << fixed;
  int x, y;
  cin >> x >> y, a = complex<long double>(x, y);
  cin >> x >> y, b = complex<long double>(x, y);
  cin >> v_max >> t;
  cin >> x >> y, v = complex<long double>(x, y);
  cin >> x >> y, w = complex<long double>(x, y);
  long double low = 0, high = 1e9, mid, ans;
  while (high - low > 1e-9) {
    mid = (low + high) / 2.0;
    if (check(mid))
      high = ans = mid;
    else
      low = mid;
  }
  cout << ans;
  return 0;
}
