#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-7, oo = 1e9;
const int maxn = 3001;
double X1, Y1, X2, Y2, vx, vy, wx, wy, t, v, l, r, ooo, cnt;
double sqr(double x) { return x * x; }
bool ok(long double tt) {
  long double x =
      X1 + vx * min((long double)t, tt) + wx * max(tt - t, (long double)0);
  long double y =
      Y1 + vy * min((long double)t, tt) + wy * max(tt - t, (long double)0);
  return sqr(x - X2) + sqr(y - Y2) < sqr(v * tt);
}
int main() {
  scanf("%lf%lf%lf%lf", &X1, &Y1, &X2, &Y2);
  scanf("%lf%lf", &v, &t);
  scanf("%lf%lf", &vx, &vy);
  scanf("%lf%lf", &wx, &wy);
  long double l = 0, r = oo;
  while (r - l > eps) {
    long double mid = (l + r) / 2;
    if (ok(mid))
      r = mid;
    else
      l = mid;
    cnt++;
    if (cnt == 100) ooo++;
    if (cnt == 1000) ooo++;
  }
  double ans = l;
  printf("%.10lf", ans);
  return 0;
}
