#include <bits/stdc++.h>
using namespace std;
const long double eps = 1e-8;
bool EQ(long double a, long double b) { return fabs(a - b) <= eps; }
bool LT(long double a, long double b) { return b - a > eps; }
bool LE(long double a, long double b) { return LT(a, b) || EQ(a, b); }
long double x1_, y1_, x2_, y2_, vmax, t, vx, vy, wx, wy, x, y;
long double my_hypot(long double a, long double b) {
  return sqrt(a * a + b * b);
}
bool check(long double a, long double b) { return LE(my_hypot(a, b), vmax); }
bool f(long double t1) {
  if (LE(t1, t))
    return check((x / t1) - vx, (y / t1) - vy);
  else {
    long double r2 = vmax * t1;
    long double o1x = x1_ + vx * t, o1y = y1_ + vy * t;
    long double o2x = wx * (t1 - t) + o1x, o2y = wy * (t1 - t) + o1y;
    return LT(my_hypot(o2x - x2_, o2y - y2_), r2);
  }
}
int main() {
  cout.precision(10);
  cin >> x1_ >> y1_ >> x2_ >> y2_ >> vmax >> t >> vx >> vy >> wx >> wy;
  x = x2_ - x1_, y = y2_ - y1_;
  long double l = 0, r = 1e9;
  while (r - l > eps) {
    long double m = (l + r) / 2;
    if (f(m))
      r = m;
    else
      l = m;
  }
  cout << r << endl;
  return 0;
}
