#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;
double calc_time(double angle) {
  double invs = vx * cos(angle + M_PI / 2) + vy * sin(angle + M_PI / 2);
  double s1 =
      vx * cos(angle) + vy * sin(angle) + sqrt(vmax * vmax - invs * invs);
  double tx = var_x1 + t * s1 * cos(angle);
  double ty = var_y1 + t * s1 * sin(angle);
  double dist = hypot(var_x2 - tx, var_y2 - ty);
  double angle2 = atan2(var_y2 - ty, var_x2 - tx);
  double invs2 = wx * cos(angle2 + M_PI / 2) + wy * sin(angle2 + M_PI / 2);
  return t + dist / (wx * cos(angle2) + wy * sin(angle2) +
                     sqrt(vmax * vmax - invs2 * invs2));
}
void solve() {
  cin >> var_x1 >> var_y1 >> var_x2 >> var_y2 >> vmax >> t >> vx >> vy >> wx >>
      wy;
  double angle = atan2(var_y2 - var_y1, var_x2 - var_x1);
  double dist = hypot(var_x2 - var_x1, var_y2 - var_y1);
  double invs = vx * cos(angle + M_PI / 2) + vy * sin(angle + M_PI / 2);
  double t1 = dist / (vx * cos(angle) + vy * sin(angle) +
                      sqrt(vmax * vmax - invs * invs));
  if (t1 < t + eps) {
    printf("%.10lf\n", t1);
    return;
  }
  double l = angle - M_PI / 2, r = angle + M_PI / 2;
  for (int i = 0; i < 1000; ++i) {
    double ll = l + (r - l) / 3;
    double rr = r - (r - l) / 3;
    if (calc_time(ll) < calc_time(rr))
      r = rr;
    else
      l = ll;
  }
  printf("%.10lf\n", calc_time((l + r) / 2));
}
int main() {
  solve();
  return 0;
}
