#include <bits/stdc++.h>
using namespace std;
const int N = 1000005;
double dist(double x1, double y1, double x2, double y2) {
  double xx = x1 - x2;
  double yy = y1 - y2;
  return sqrt(xx * xx + yy * yy);
}
int main() {
  int x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  int v, t;
  cin >> v >> t;
  int vx, vy, wx, wy;
  cin >> vx >> vy >> wx >> wy;
  double le = 0, ri = 1e15;
  for (int it = 0; it < 80; it++) {
    double mid = (le + ri) / 2;
    double x = x1;
    double y = y1;
    x += min(1.0 * t, mid) * vx;
    y += min(1.0 * t, mid) * vy;
    x += max(0.0, mid - t) * wx;
    y += max(0.0, mid - t) * wy;
    double total = dist(x, y, x2, y2) / v;
    if (total - 1e-9 <= mid) {
      ri = mid;
    } else {
      le = mid;
    }
  }
  printf("%.10f\n", ri);
  return 0;
}
