#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 9;
const int mod1 = 999999937;
const int inf = 2e9;
const int MAXN = 1e3 + 5;
const double eps = 1e-4;
struct point {
  long double x, y;
};
long double dist(point a, point b) {
  return sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));
}
int main() {
  point s, f, u1, u2;
  long double t, v;
  cin >> s.x >> s.y >> f.x >> f.y >> v >> t >> u1.x >> u1.y >> u2.x >> u2.y;
  long double m, l = 0, r = 1e9;
  for (int i = 0; i < 100; i++) {
    m = (l + r) / 2;
    point q;
    if (m <= t) {
      q.x = u1.x * m + s.x;
      q.y = u1.y * m + s.y;
    } else {
      q.x = u1.x * t + s.x + (m - t) * u2.x;
      q.y = u1.y * t + s.y + (m - t) * u2.y;
    }
    long double d = dist(q, f);
    if (d / v <= m) {
      r = m;
    } else {
      l = m;
    }
  }
  cout << fixed << setprecision(7);
  cout << r;
  return 0;
}
