#include <bits/stdc++.h>
using namespace std;
int main() {
  double x1, y1, x2, y2;
  double v, t, vx, vy, wx, wy;
  while (~scanf("%lf%lf%lf%lf%lf%lf%lf%lf%lf%lf", &x1, &y1, &x2, &y2, &v, &t,
                &vx, &vy, &wx, &wy)) {
    double l = 0, r = 1e9, m;
    for (int i = 1; i <= 100; i++) {
      m = (l + r) / 2;
      double x = x1 + vx * min(m, t) + wx * max(m - t, 0.0);
      double y = y1 + vy * min(m, t) + wy * max(m - t, 0.0);
      double dist = sqrt((x - x2) * (x - x2) + (y - y2) * (y - y2));
      if (dist <= v * m)
        r = m;
      else
        l = m;
    }
    printf("%.18lf\n", l);
  }
  return 0;
}
