#include <bits/stdc++.h>
using namespace std;
double dist(double xx1, double yy1, double xx2, double yy2) {
  return sqrt((xx1 - xx2) * (xx1 - xx2) + (yy1 - yy2) * (yy1 - yy2));
}
double xx1, yy1, xx2, yy2;
double vmax, t;
double w1x, w1y, w2x, w2y;
double d;
bool check(double cur) {
  double x = xx2 - xx1, y = yy2 - yy1;
  x -= min(cur, t) * w1x + max(0.0, cur - t) * w2x;
  y -= min(cur, t) * w1y + max(0.0, cur - t) * w2y;
  double cd = dist(0, 0, x, y);
  return (cd < cur * vmax);
}
double bs(double l, double r) {
  if (r - l <= 1e-8) return (l + r) / 2;
  double mid = (l + r) / 2;
  if (check(mid))
    return bs(l, mid);
  else
    return bs(mid, r);
}
int main() {
  cin >> xx1 >> yy1 >> xx2 >> yy2;
  cin >> vmax >> t;
  cin >> w1x >> w1y >> w2x >> w2y;
  d = dist(xx1, yy1, xx2, yy2);
  cout << setprecision(20) << bs(0, d * 2 * vmax);
}
