#include <bits/stdc++.h>
using namespace std;
double sq(double a) { return a * a; }
int xi, yi, xf, yf;
int vmax, t;
int ux, uy, wx, wy;
bool puede(pair<double, double> a, pair<double, double> b, double dist) {
  double d = sq(a.first - b.first) + sq(a.second - b.second);
  return (d <= sq(dist));
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> xi >> yi >> xf >> yf;
  cin >> vmax >> t;
  cin >> ux >> uy;
  cin >> wx >> wy;
  double vmin = vmax - sqrt(max(sq(ux) + sq(uy), sq(wx) + sq(wy)));
  double dist = sqrt(sq(xi - xf) + sq(yi - yf));
  double mini = 0;
  double maxi = dist / vmin;
  double mid = (maxi + mini) / 2;
  double eps = 1 / 1e10;
  while (maxi >= mini + eps) {
    mid = (maxi + mini) / 2;
    double r1, r2;
    pair<double, double> c1, c2;
    if (mid <= t) {
      r1 = vmax * mid;
      r2 = 0;
      c1 = make_pair((xi + ux * mid), (yi + uy * mid));
      c2 = make_pair(xf, yf);
    } else {
      r1 = vmax * t;
      r2 = vmax * (mid - t);
      c1 = make_pair((xi + ux * t), (yi + uy * t));
      c2 = make_pair((xf - wx * (mid - t)), (yf - wy * (mid - t)));
    }
    if (puede(c1, c2, r1 + r2)) {
      maxi = mid;
    } else {
      mini = mid;
    }
  }
  cout << setprecision(15) << mid << "\n";
  return 0;
}
