#include <bits/stdc++.h>
int main() {
  double v, t, x1, y1, x2, y2, th, d, p, q, to, dis;
  scanf("%lf%lf%lf%lf", &x1, &y1, &x2, &y2);
  scanf("%lf%lf", &v, &t);
  dis = sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
  th = atan2(y2 - y1, x2 - x1);
  double vx, vy, th1, v1;
  scanf("%lf%lf", &vx, &vy);
  to = sqrt(vx * vx + vy * vy);
  th1 = atan2(vy, vx);
  d = th1 - th;
  q = to * sin(d);
  p = to * cos(d);
  v1 = sqrt(v * v - q * q) + p;
  if (dis / v1 <= t) {
    printf("%.12f", dis / v1);
    return 0;
  }
  double wx, wy, th2, v2;
  scanf("%lf%lf", &wx, &wy);
  x1 = x1 + t * (vx - wx);
  y1 = y1 + t * (vy - wy);
  dis = sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
  th = atan2(y2 - y1, x2 - x1);
  to = sqrt(wx * wx + wy * wy);
  th2 = atan2(wy, wx);
  d = th2 - th;
  q = to * sin(d);
  p = to * cos(d);
  v2 = sqrt(v * v - q * q) + p;
  printf("%.12f ", dis / v2);
}
