#include <bits/stdc++.h>
using namespace std;
double a, b, c, d, v, t, e, f, g, h, l = -1, r = 1e9, m, p, q;
int main() {
  cin >> a >> b >> c >> d >> v >> t >> e >> f >> g >> h;
  for (int i = 0; i < 500; i++) {
    m = (l + r) / 2;
    p = abs(c - a - min(m, t) * e - max(0.0, m - t) * g);
    q = abs(d - b - min(m, t) * f - max(0.0, m - t) * h);
    if (sqrt(p * p + q * q) <= m * v)
      r = m;
    else
      l = m;
  }
  printf("%.10lf", r);
  return 0;
}
