#include <bits/stdc++.h>
using namespace std;
int x1, Y1, x2, y2, vmax, t, vx, vy, wx, wy;
bool check(double mid) {
  double newx, newy;
  if (mid <= t) {
    newx = x1 * 1.0 + mid * vx;
    newy = Y1 * 1.0 + mid * vy;
  } else {
    newx = x1 * 1.0 + t * vx + (mid - t) * wx;
    newy = Y1 * 1.0 + t * vy + (mid - t) * wy;
  }
  double dist = sqrt((newx - x2 * 1.0) * (newx - x2 * 1.0) +
                     (newy - y2 * 1.0) * (newy - y2 * 1.0));
  double time = (dist * 1.0) / (vmax * 1.0);
  return time <= mid;
}
int main() {
  cin >> x1 >> Y1 >> x2 >> y2 >> vmax >> t;
  cin >> vx >> vy >> wx >> wy;
  double l = 0, r = 1e9, ans = 1e9;
  for (int i = 0; i < 1000; i++) {
    double mid = (l + r) / 2.0;
    if (check(mid)) {
      r = mid;
      ans = min(ans, mid);
    } else {
      l = mid;
    }
  }
  printf("%.12f", ans);
}
