#include <bits/stdc++.h>
using namespace std;
const long double eps = 0.00000001;
pair<long double, long double> a, b;
long double xx1, yy1, xx2, yy2;
long double vmax, t;
inline long double f(long double mid) {
  long double px, py;
  px = xx1;
  py = yy1;
  if (mid >= t) {
    px += a.first * t;
    py += a.second * t;
    px += b.first * (mid - t);
    py += b.second * (mid - t);
  } else {
    px += a.first * mid;
    py += a.second * mid;
  }
  long double len = ((px - xx2) * (px - xx2) + (py - yy2) * (py - yy2));
  len /= vmax * vmax;
  if (len / mid > mid) return false;
  return true;
}
int main(int argc, const char* argv[]) {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> xx1 >> yy1 >> xx2 >> yy2;
  cin >> vmax >> t;
  cin >> a.first >> a.second;
  cin >> b.first >> b.second;
  long double l = 0;
  long double r = 1e9;
  for (int it = 0; it <= 700; ++it) {
    long double mid = (l + r) / 2.;
    if (f(mid))
      r = mid;
    else
      l = mid;
  }
  cout << fixed << setprecision(6) << l << '\n';
}
