#include <bits/stdc++.h>
using namespace std;
double eps = 1e-9;
double dis(double x1, double yy1, double x2, double y2) {
  return sqrt((x1 - x2) * (x1 - x2) + (yy1 - y2) * (yy1 - y2));
}
double yy1;
double x1, x2, y2, v, t, vx, vy, wx, wy;
int check(double tt) {
  double xx = x2, yy = y2;
  if (tt <= t) {
    xx = xx + -vx * tt;
    yy = yy + -vy * tt;
  } else {
    xx = xx + -vx * t + -wx * (tt - t);
    yy = yy + -vy * t + -wy * (tt - t);
  }
  if (dis(x1, yy1, xx, yy) <= tt * v) return 1;
  return 0;
}
int main() {
  cin >> x1 >> yy1 >> x2 >> y2 >> v >> t >> vx >> vy >> wx >> wy;
  double l = 0.00, r = t;
  for (int i = 1; i <= 1000; i++) {
    double mid = (l + r) / 2.0;
    if (check(mid))
      r = mid;
    else
      l = mid;
  }
  if (check(t)) {
    printf("%.12lf\n", l);
    return 0;
  }
  l = t, r = 9999999999.0;
  for (int i = 1; i <= 1000; i++) {
    double mid = (l + r) / 2.0;
    if (check(mid))
      r = mid;
    else
      l = mid;
  }
  printf("%.12lf\n", l);
}
