#include <bits/stdc++.h>
using namespace std;
int x1, x2, yy1, y2, v1, v2, u1, u2, v, ti;
double dis(double x1, double yy1, double x2, double y2) {
  return (x1 - x2) * (x1 - x2) + (yy1 - y2) * (yy1 - y2);
}
int main() {
  scanf("%d%d%d%d%d%d%d%d%d%d", &x1, &yy1, &x2, &y2, &v, &ti, &v1, &u1, &v2,
        &u2);
  double l = 0, r = 1e9, ans;
  int t = 1e7;
  while (t--) {
    double mid = 0.5 * (l + r);
    double nx = x2, ny = y2;
    if (ti < mid)
      nx -= v1 * ti + v2 * (mid - ti), ny -= u1 * ti + u2 * (mid - ti);
    else
      nx -= v1 * mid, ny -= u1 * mid;
    if (dis(double(x1), double(yy1), nx, ny) <= mid * v * mid * v)
      ans = mid, r = mid;
    else
      l = mid;
  }
  printf("%.10f\n", ans);
  return 0;
}
