#include <bits/stdc++.h>
using namespace std;
int main() {
  long double x1, y1, x2, y2, vmax, t, vx, vy, wx, wy;
  cin >> x1 >> y1 >> x2 >> y2 >> vmax >> t >> vx >> vy >> wx >> wy;
  long double low = 0, high = 1e18;
  for (int its = 0; its < 500; its++) {
    long double m = (low + high) / 2;
    long double dx = x2, dy = y2;
    dx += min(m, t) * (-vx);
    dy += min(m, t) * (-vy);
    if (m > t) {
      long double dt = m - t;
      dx += dt * (-wx);
      dy += dt * (-wy);
    }
    long double dist = hypotl(x1 - dx, y1 - dy);
    if (dist / vmax <= m)
      high = m;
    else
      low = m;
  }
  cout << fixed << setprecision(20) << (low + high) / 2 << endl;
  return 0;
}
