#include <bits/stdc++.h>
using namespace std;
int main() {
  double a, b, c, d, e, f, v, t, g, h;
  cin >> a >> b >> c >> d >> v >> t >> e >> f >> g >> h;
  double l = 0, r = 100000000;
  for (int i = 0; i < 200; i++) {
    double m = (l + r) / 2;
    double j = c - min(m, t) * e - max(0.0, m - t) * g;
    double k = d - min(m, t) * f - max(0.0, m - t) * h;
    double dis = sqrt((j - a) * (j - a) + (k - b) * (k - b));
    if (dis < m * v)
      r = m;
    else
      l = m;
  }
  printf("%.10f\n", l);
  return 0;
}
