#include <bits/stdc++.h>
using namespace std;
double x[5], y[5], v, t;
double vx, vy, wx, wy;
double dist(double a, double b, double c, double e) {
  return sqrt((abs(a - c) * abs(a - c)) + (abs(b - e) * abs(b - e)));
}
bool C(double mid) {
  double d = dist(x[1] + min(mid, t) * vx, y[1] + min(mid, t) * vy, x[2], y[2]);
  if (mid <= t) return mid >= (d / v);
  double left = mid - t;
  double xx = x[1] + t * vx, yy = y[1] + t * vy;
  double dd = dist(xx + left * wx, yy + left * wy, x[2], y[2]);
  return mid >= (dd / v);
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> x[1] >> y[1] >> x[2] >> y[2];
  cin >> v >> t;
  cin >> vx >> vy;
  cin >> wx >> wy;
  if (x[1] == x[2] && y[1] == y[2]) {
    cout << "0.0000000" << '\n';
    return 0;
  }
  double lb = 0., ub = 1e10;
  for (int(i) = 0; (i) < (200); i++) {
    double mid = (lb + ub) / 2.;
    if (C(mid))
      ub = mid;
    else
      lb = mid;
  }
  cout << fixed << setprecision(15) << ub << '\n';
  return 0;
}
