#include <bits/stdc++.h>
using namespace std;
pair<double, double> from, to, w1, w2;
double v, t;
double pw(double a) { return a * a; }
double dist(double x1, double y1, double x2, double y2) {
  return sqrt(pw(x1 - x2) + pw(y1 - y2));
}
int canReach(double tm) {
  double x = from.first;
  double y = from.second;
  x += min(tm, t) * w1.first;
  y += min(tm, t) * w1.second;
  if (tm > t) {
    double tt = tm - t;
    x += tt * w2.first;
    y += tt * w2.second;
  }
  double d = dist(x, y, to.first, to.second);
  return d / v <= tm;
}
int main() {
  cin >> from.first >> from.second;
  cin >> to.first >> to.second;
  cin >> v >> t;
  cin >> w1.first >> w1.second;
  cin >> w2.first >> w2.second;
  double lo = 0., hi = 1000000000.0;
  while (hi - lo > 1e-7) {
    double md = (hi + lo) / 2;
    if (canReach(md)) {
      hi = md;
    } else {
      lo = md;
    }
  }
  cout << setprecision(7) << fixed << (hi + lo) / 2 << endl;
  return 0;
}
