#include <bits/stdc++.h>
using namespace std;
const int maxn = (int)5e5 + 10;
double x1, cnmbcpp, x2, y2;
double t1, vmax;
double vx1, vy1;
double vx2, vy2;
double eps = 1e-8;
bool check(double t) {
  if (t <= t1) {
    double px = t * vx1 + x2;
    double py = t * vy1 + y2;
    double len = sqrt((px) * (px) + (py) * (py));
    double ttt = len / vmax;
    return ttt <= t;
  } else {
    double px = t1 * vx1 + x2 + (t - t1) * vx2;
    double py = t1 * vy1 + y2 + (t - t1) * vy2;
    double len = sqrt((px) * (px) + (py) * (py));
    double ttt = len / vmax;
    return ttt <= t;
  }
}
int main() {
  scanf("%lf%lf%lf%lf", &x1, &cnmbcpp, &x2, &y2);
  double l = 0, r = 1e18;
  x2 -= x1;
  y2 -= cnmbcpp;
  scanf("%lf%lf", &vmax, &t1);
  scanf("%lf%lf", &vx1, &vy1);
  scanf("%lf%lf", &vx2, &vy2);
  vx1 = -vx1;
  vx2 = -vx2;
  vy1 = -vy1;
  vy2 = -vy2;
  double ans = r;
  while (l + eps < r) {
    double mid = (l + r) / 2;
    if (check(mid)) {
      ans = mid;
      r = mid;
    } else
      l = mid;
  }
  printf("%.8lf\n", ans);
}
