#include <bits/stdc++.h>
using namespace std;
double xx1, yy1, xx2, yy2;
double vmax, t;
double vx, vy;
double wx, wy;
static double eps = 1e-8;
bool isPossible(double tt) {
  double posx = xx1, posy = yy1;
  if (tt > t) {
    posx += vx * t + wx * (tt - t);
    posy += vy * t + wy * (tt - t);
  } else {
    posx += vx * tt;
    posy += vy * tt;
  }
  double lenx = (xx2 - posx);
  double leny = (yy2 - posy);
  double len = sqrt(lenx * lenx + leny * leny);
  return tt >= len / vmax;
}
double search(double b, double e) {
  while (e - b > eps) {
    double m = (e - b) / 2 + b;
    if (isPossible(m)) {
      e = m;
    } else {
      b = m;
    }
  }
  return b;
}
double size(double x, double y) { return sqrt(x * x + y * y); }
void solve() {
  double lenx = (xx2 - xx1), leny = (yy2 - yy1);
  double len = sqrt(lenx * lenx + leny * leny);
  printf("%.18f\n", search(0, len / eps));
}
int main() {
  cin >> xx1 >> yy1 >> xx2 >> yy2;
  cin >> vmax >> t;
  cin >> vx >> vy;
  cin >> wx >> wy;
  solve();
  return 0;
}
