#include <bits/stdc++.h>
using namespace std;
const long long mod = 1000000007;
const long long INF = (long long)1000000007 * 1000000007;
const long double eps = 1e-8;
const long double pi = acos(-1.0);
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(18);
  long double x1, x2, y1, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  long double gx = x2 - x1, gy = y2 - y1;
  long double the1 = atan2(y2 - y1, x2 - x1);
  long double dis = sqrt((pow(y2 - y1, 2) + pow((x2 - x1), 2)));
  long double vm, t;
  cin >> vm >> t;
  long double v[2];
  long double wx[2], wy[2];
  for (int aa = 0; aa < 2; aa++) {
    cin >> wx[aa] >> wy[aa];
    long double vx = wx[aa], vy = wy[aa];
    long double the2 = atan2(vy, vx);
    long double d2 = sqrt((pow(vy, 2) + pow(vx, 2)));
    v[aa] = d2 * cos(the1 - the2) +
            sqrt(pow(d2, 2) * (pow(cos(the1 - the2), 2) - 1) + pow(vm, 2));
  }
  long double out = INF;
  if (dis < t * v[0]) {
    out = dis / v[0];
  } else {
    long double a2 = pow(vm, 2) - (pow(wx[1], 2) + pow(wy[1], 2));
    long double a1 = 0;
    a1 += 2 * wx[1] * (gx - t * (wx[0] - wx[1]));
    a1 += 2 * wy[1] * (gy - t * (wy[0] - wy[1]));
    long double a0 = 0;
    a0 -= pow(gx - t * (wx[0] - wx[1]), 2);
    a0 -= pow(gy - t * (wy[0] - wy[1]), 2);
    out = (-a1 + sqrt(a1 * a1 - 4 * a0 * a2)) / (2 * a2);
  }
  cout << out << endl;
  return 0;
}
