#include <bits/stdc++.h>
using namespace std;
const int N = 310;
const int inf = 1e9;
double x1, var1, x2, y2, v, t, vx, vy, wx, wy;
bool check(double T) {
  if (t > T) {
    double x = x1 + T * vx;
    double y = var1 + T * vy;
    double d = sqrt((x - x2) * (x - x2) + (y - y2) * (y - y2));
    return (d / v <= T);
  } else {
    double x = x1 + t * vx + (T - t) * wx;
    double y = var1 + t * vy + (T - t) * wy;
    double d = sqrt((x - x2) * (x - x2) + (y - y2) * (y - y2));
    return (d / v <= T);
  }
}
int main() {
  cin >> x1 >> var1 >> x2 >> y2;
  cin >> v >> t;
  cin >> vx >> vy;
  cin >> wx >> wy;
  double l = 0, r = 1e18;
  for (int i = 1; i <= 300; i++) {
    double m = (l + r) / 2;
    if (check(m))
      r = m;
    else
      l = m;
  }
  cout << fixed << setprecision(9) << l;
  return 0;
}
