#include <bits/stdc++.h>
using namespace std;
double sqr(double a) { return a * a; }
int main() {
  double x1, y1, x2, y2;
  double v, t;
  double vx, vy;
  double wx, wy;
  cin >> x1 >> y1 >> x2 >> y2;
  cin >> v >> t;
  cin >> vx >> vy;
  cin >> wx >> wy;
  double l = 0, r = 1000000000;
  for (int i = 0; i < 1000000; i++) {
    double m = (l + r) / 2;
    double dx = min(m, t) * vx + max((double)0, m - t) * wx;
    double dy = min(m, t) * vy + max((double)0, m - t) * wy;
    double len = sqrt(sqr(x1 + dx - x2) + sqr(y1 + dy - y2));
    if (len <= v * m)
      r = m;
    else
      l = m;
  }
  printf("%.12lf", l);
  return 0;
}
