#include <bits/stdc++.h>
using namespace std;
double x, x2, y, y2;
double v, t, vx, vy;
double wx, wy, Ex, Ey;
bool check(double mid) {
  double tempx = vx * min(mid, t), tempy = vy * min(t, mid);
  if (mid > t) tempx += (wx * (mid - t)), tempy += (wy * (mid - t));
  double ba2ex = (Ex - tempx), ba2ey = (Ey - tempy);
  double dis = sqrt((ba2ex * ba2ex) + (ba2ey * ba2ey));
  return (dis / mid <= v);
}
double BS() {
  double l = 0, r = 1e10, mid, ret;
  for (int i = 0; i < 500; ++i) {
    mid = (l + r) / 2.0;
    if (check(mid))
      ret = mid, r = mid;
    else
      l = mid;
  }
  return ret;
}
int main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  ;
  cin >> x >> y;
  cin >> x2 >> y2;
  cin >> v >> t;
  cin >> vx >> vy;
  cin >> wx >> wy;
  Ex = x2 - x;
  Ey = y2 - y;
  cout << fixed << setprecision(18) << BS() << endl;
  return 0;
}
