#include <bits/stdc++.h>
using namespace std;
long double x, y, x2, y2, vx, vy, v, t, wx, wy;
long long l, r;
bool check(long long k) {
  long double t1 = (long double)k / 100000000.0;
  if (t1 > t) {
    long double dis =
        ((x - x2 + vx * t + wx * (t1 - t)) * (x - x2 + vx * t + wx * (t1 - t)) +
         (y - y2 + vy * t + wy * (t1 - t)) * (y - y2 + vy * t + wy * (t1 - t)));
    if (v * t1 * v * t1 >= dis) return 1;
    return 0;
  } else {
    long double dis = ((x - x2 + vx * t1) * (x - x2 + vx * t1) +
                       (y - y2 + vy * t1) * (y - y2 + vy * t1));
    if (v * t1 * v * t1 >= dis) return 1;
    return 0;
  }
}
int main() {
  cin >> x >> y >> x2 >> y2;
  cin >> v >> t;
  cin >> vx >> vy;
  cin >> wx >> wy;
  l = 1;
  r = 10000000000000000;
  while (l < r) {
    long long mid = (l + r) / 2;
    if (check(mid))
      r = mid;
    else
      l = mid;
    if (l + 1 == r) break;
  }
  long double ans = (long double)l / 100000000.0;
  cout << fixed << setprecision(9) << ans;
}
