#include <bits/stdc++.h>
using namespace std;
int main() {
  double x1, y1, x2, y2, vmax, tvento, vx, vy, wx, wy;
  cin >> x1 >> y1 >> x2 >> y2 >> vmax >> tvento >> vx >> vy >> wx >> wy;
  vmax = vmax * vmax;
  double l = 0, r = 1000000000;
  while (l < r - 1E-6) {
    double x = x1, y = y1, t = (r + l) / 2;
    x += min(t, tvento) * vx + max(0.0, t - tvento) * wx;
    y += min(t, tvento) * vy + max(0.0, t - tvento) * wy;
    double velocidade = ((x2 - x) * (x2 - x) + (y2 - y) * (y2 - y)) / (t * t);
    if (velocidade < vmax) {
      r = t;
    } else {
      l = t;
    }
  }
  printf("%.12f\n", l);
  return 0;
}
