#include <bits/stdc++.h>
using namespace std;
template <class T>
bool uin(T &a, T b) {
  return a > b ? (a = b, true) : false;
}
template <class T>
bool uax(T &a, T b) {
  return a < b ? (a = b, true) : false;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.precision(10);
  cout << fixed;
  double x1, y1, x2, y2, v, t, vx, vy, wx, wy;
  cin >> x1 >> y1 >> x2 >> y2 >> v >> t >> vx >> vy >> wx >> wy;
  double L = 0.0, R = 1e9;
  for (int its = 0; its < (int)(100); ++its) {
    double M = 0.5 * (L + R);
    double x = x1 + min(M, t) * vx + max(M - t, 0.0) * wx;
    double y = y1 + min(M, t) * vy + max(M - t, 0.0) * wy;
    (hypot(x - x2, y - y2) < v * M ? R : L) = M;
  }
  cout << R << '\n';
  return 0;
}
