#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-8;
int xs, ys, xt, yt;
int v, t;
int vx, vy;
int wx, wy;
double calc(double vx, double vy, double th, double len) {
  double vxl = vx * cos(th);
  double vxt = vx * sin(th);
  double vyl = vy * sin(th);
  double vyt = vy * cos(th);
  double vl = sqrt(((v) * (v)) - ((vyt - vxt) * (vyt - vxt)));
  ;
  ;
  ;
  return len / (vl + vxl + vyl);
}
double calcv(double t2) {
  double xtt = (double)xt - t * vx;
  double ytt = (double)yt - t * vy;
  xtt -= t2 * wx;
  ytt -= t2 * wy;
  double ll = sqrt(((xtt - xs) * (xtt - xs)) + ((ytt - ys) * (ytt - ys)));
  return ll / (t2 + t);
}
int main() {
  scanf("%d%d%d%d", &xs, &ys, &xt, &yt);
  scanf("%d%d", &v, &t);
  scanf("%d%d", &vx, &vy);
  scanf("%d%d", &wx, &wy);
  double th = atan2(yt - ys, xt - xs);
  double len = sqrt(((xs - xt) * (xs - xt)) + ((ys - yt) * (ys - yt)));
  double t1 = calc(vx, vy, th, len);
  ;
  if (t1 <= t + eps) {
    printf("%.8f\n", t1);
  } else {
    double s = len * (t1 - t) / t1;
    double t2 = calc(wx, wy, th, s);
    double l = 0, r = t2;
    for (int i = 0; i < 50; ++i) {
      double mid = (l + r) / 2;
      if (calcv(mid) > v) {
        l = mid;
      } else {
        r = mid;
      }
    }
    printf("%.8f\n", t + l);
  }
  return 0;
}
