#include <bits/stdc++.h>
using namespace std;
void solve();
int main() {
  solve();
  return 0;
}
void solve() {
  long double x1, x2, y1, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  long double vm, t;
  cin >> vm >> t;
  long double vx, vy, wx, wy;
  cin >> vx >> vy >> wx >> wy;
  long double v1 = sqrt(vx * vx + vy * vy);
  long double l = sqrt(((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)));
  long double a = vm * vm - v1 * v1;
  long double ccos = ((x2 - x1) * vx + (y2 - y1) * vy);
  long double b = 2 * ccos;
  long double c = -l * l;
  long double t1 = (-b + sqrt(b * b - 4 * a * c)) / a / 2;
  long double t2 = (-b - sqrt(b * b - 4 * a * c)) / a / 2;
  if ((t1 >= 0 && t1 <= t) || (t2 >= 0 && t2 <= t)) {
    if (t2 < 0)
      t1 = t1;
    else if (t1 < 0)
      t1 = t2;
    else
      t1 = min(t1, t2);
    double res = t1;
    printf("%.15lf\n", res);
    return;
  }
  x1 = x1 + t * vx;
  y1 = y1 + t * vy;
  l = sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
  v1 = sqrt(wx * wx + wy * wy);
  a = vm * vm - v1 * v1;
  ccos = ((x2 - x1) * wx + (y2 - y1) * wy);
  b = 2 * ccos + 2 * vm * vm * t;
  c = -l * l + vm * vm * t * t;
  t1 = (-b + sqrt(b * b - 4 * a * c)) / a / 2;
  t2 = (-b - sqrt(b * b - 4 * a * c)) / a / 2;
  if (t2 < 0)
    t1 = t1;
  else if (t1 < 0)
    t1 = t2;
  else
    t1 = min(t1, t2);
  double res = t1 + t;
  printf("%.20lf", res);
}
