#include <bits/stdc++.h>
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
signed main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cout << fixed << setprecision(20);
  const long long INF = 1e9;
  long long x1, x2, y1, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  double x = x2 - x1, y = y2 - y1;
  double v, T;
  cin >> v >> T;
  long long vx, vy, ux, uy;
  cin >> vx >> vy >> ux >> uy;
  auto check = [&](double t) {
    double t1 = min(t, T);
    double t2 = t - t1;
    double dx = t1 * vx + t2 * ux;
    double dy = t1 * vy + t2 * uy;
    double d = sqrt(((x - dx) * (x - dx)) + ((y - dy) * (y - dy)));
    return d / v <= t;
  };
  double l = 0, r = INF;
  for (long long i = 0; i < 100; i++) {
    double m = (l + r) / 2;
    if (check(m))
      r = m;
    else
      l = m;
  }
  cout << (l + r) / 2;
}
