#include <bits/stdc++.h>
using namespace std;
int main() {
  cin.tie(0);
  int i, n, e;
  double x1, y1, x2, y2, vmax, t, vx, vy, wx, wy;
  cin >> x1 >> y1 >> x2 >> y2;
  cin >> vmax >> t;
  cin >> vx >> vy;
  cin >> wx >> wy;
  double sid;
  double l = 0.0, r = (double)1e9;
  double eps = 1e-7;
  double x, y;
  while (r - l > eps) {
    sid = (r + l) / 2.0;
    if (sid < t) {
      x = x1 + sid * vx;
      y = y1 + sid * vy;
    } else {
      x = x1 + t * vx + (sid - t) * wx;
      y = y1 + t * vy + (sid - t) * wy;
    }
    double val;
    val = (x2 - x) * (x2 - x) + (y2 - y) * (y2 - y);
    val = sqrt(val);
    if (val < vmax * sid) {
      r = sid;
    } else
      l = sid;
  }
  cout << setprecision(8);
  cout << fixed;
  cout << r << "\n";
  return 0;
}
