#include <bits/stdc++.h>
double xx, yy, l, r, m;
int x1, yy1, x2, y2, vx, vy, ux, uy, ti, v, t;
double dist(double x1, double y1, double x2, double y2) {
  return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}
int main() {
  scanf("%d%d%d%d", &x1, &yy1, &x2, &y2);
  scanf("%d%d", &v, &t);
  scanf("%d%d", &ux, &uy);
  scanf("%d%d", &vx, &vy);
  l = 0;
  r = 0x37373737;
  while (ti <= 70) {
    ti++;
    m = (l + r) / 2;
    if (m <= t)
      xx = x1 + m * ux, yy = yy1 + m * uy;
    else
      xx = x1 + t * ux + (m - t) * vx, yy = yy1 + t * uy + (m - t) * vy;
    if (dist(xx, yy, x2, y2) <= m * v)
      r = m;
    else
      l = m;
  }
  printf("%.9lf", l);
}
