#include <bits/stdc++.h>
using namespace std;
const int INF = 987654321;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.precision(13);
  cout << fixed;
  double x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  double vmax, t;
  cin >> vmax >> t;
  double vx, vy;
  double wx, wy;
  cin >> vx >> vy;
  cin >> wx >> wy;
  x2 -= x1;
  y2 -= y1;
  double lo = 0, hi = 1e18;
  for (int k = 0; k < 100; ++k) {
    double tt = (lo + hi) / 2;
    double xp, yp;
    if (tt <= t) {
      xp = x2 - tt * vx;
      yp = y2 - tt * vy;
    } else {
      xp = x2 - t * vx - (tt - t) * wx;
      yp = y2 - t * vy - (tt - t) * wy;
    }
    double len = sqrt(xp * xp + yp * yp);
    if (vmax * tt >= len)
      hi = tt;
    else
      lo = tt;
  }
  cout << lo << '\n';
  return 0;
}
