#include <bits/stdc++.h>
using namespace std;
signed main() {
  std::ios::sync_with_stdio(false);
  cin.tie(0);
  int x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  int x = x2 - x1;
  int y = y2 - y1;
  int v, t, vx, vy, wx, wy;
  cin >> v >> t >> vx >> vy >> wx >> wy;
  auto check = [&](long double tt) {
    long double dx =
        min((long double)t, tt) * vx + max((long double)0, tt - t) * wx;
    long double dy =
        min((long double)t, tt) * vy + max((long double)0, tt - t) * wy;
    return sqrt((x - dx) * (x - dx) + (y - dy) * (y - dy)) / tt <= v;
  };
  if (check(0)) {
    cout << "0\n";
    return 0;
  }
  long double l = 0, r = 1;
  while (!check(r)) r = 2 * r;
  for (int ii = 0; ii < 100; ii++) {
    long double m = (l + r) / 2;
    if (check(m))
      r = m;
    else
      l = m;
  }
  cout << setprecision(20) << r << "\n";
}
