#include <bits/stdc++.h>
using namespace std;
double X1, Y1, X2, Y2, maxV, T, vx, vy, wx, wy, l = 0, r = 1e20, x, y, mi, dis;
int main() {
  cin >> X1 >> Y1 >> X2 >> Y2 >> maxV >> T >> vx >> vy >> wx >> wy;
  for (int i = 0; i < (int)10000; ++i) {
    mi = (l + r) / 2;
    if (mi <= T) {
      x = X1 + vx * mi;
      y = Y1 + vy * mi;
    } else {
      x = X1 + vx * T + wx * (mi - T);
      y = Y1 + vy * T + wy * (mi - T);
    }
    dis = hypot(x - X2, y - Y2);
    (dis >= maxV * mi ? l : r) = mi;
  }
  printf("%0.18f\n", l);
}
