#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-7;
double var_x1, var_y1, var_x2, var_y2, vmax, t, vx, vy, wx, wy;
void solve() {
  cin >> var_x1 >> var_y1 >> var_x2 >> var_y2 >> vmax >> t >> vx >> vy >> wx >>
      wy;
  double l = 0, r = 1e9;
  for (int i = 0; i < 1000; ++i) {
    double m = (l + r) / 2;
    double by_x = var_x1 + (vx * min(m, t) + wx * max(0., m - t));
    double by_y = var_y1 + (vy * min(m, t) + wy * max(0., m - t));
    if (hypot(var_x2 - by_x, var_y2 - by_y) / vmax <= m)
      r = m;
    else
      l = m;
  }
  printf("%.10lf\n", (l + r) / 2);
}
int main() {
  solve();
  return 0;
}
