#include <bits/stdc++.h>
using namespace std;
const double EPS = 1.e-8;
double _x1, _y1, _x2, _y2, v, t, vx, vy, wx, wy;
bool can(double s) {
  pair<double, double> w(0, 0);
  if (s < t)
    w = make_pair(vx * s, vy * s);
  else
    w = make_pair(vx * t + wx * (s - t), vy * t + wy * (s - t));
  pair<double, double> init(_x1 + w.first, _y1 + w.second);
  double far = hypot(_x2 - init.first, _y2 - init.second);
  if (far / v < s) return true;
  return false;
}
int main() {
  cin.sync_with_stdio(false);
  cin >> _x1 >> _y1 >> _x2 >> _y2 >> v >> t >> vx >> vy >> wx >> wy;
  double lo = 0, hi = 1000000000;
  for (int x = 100; x-- > 0;) {
    double mid = (lo + hi) / 2;
    if (can(mid))
      hi = mid;
    else
      lo = mid;
  }
  cout << setprecision(15) << lo << endl;
  return 0;
}
