#include <bits/stdc++.h>
using namespace std;
double nx, ny, mx, my;
double vx, t;
double vx1, vy1, vx2, vy2;
bool judge(double t1) {
  double x, y;
  x = nx + vx1 * min(t1, t);
  y = ny + vy1 * min(t1, t);
  if (t1 >= t) {
    x += (t1 - t) * vx2;
    y += (t1 - t) * vy2;
  }
  double len = sqrt((x - mx) * (x - mx) + (y - my) * (y - my));
  double tt = len / vx;
  return tt <= t1;
}
double devide() {
  double l = 0, r = 1e50, ans;
  for (int i = 1; i <= 10000; i++) {
    double mid = (l + r) / 2;
    if (judge(mid)) {
      r = mid;
      ans = mid;
    } else {
      l = mid;
    }
  }
  return ans;
}
int main() {
  cin >> nx >> ny >> mx >> my;
  cin >> vx >> t;
  cin >> vx1 >> vy1;
  cin >> vx2 >> vy2;
  printf("%.18f", devide());
  return 0;
}
