#include <bits/stdc++.h>
using namespace std;
long double x1, y11, x2, y2;
long double vmx, t;
long double vx, vy, wx, wy;
int ok(double tt) {
  long double sx1, sy1;
  if (tt < t) {
    sx1 = x1 + tt * vx;
    sy1 = y11 + tt * vy;
  } else {
    sx1 = x1 + t * vx + (tt - t) * wx;
    sy1 = y11 + t * vy + (tt - t) * wy;
  }
  return (vmx * tt >= sqrt((x2 - sx1) * (x2 - sx1) + (y2 - sy1) * (y2 - sy1)));
}
int main() {
  cin >> x1 >> y11 >> x2 >> y2;
  cin >> vmx >> t;
  cin >> vx >> vy >> wx >> wy;
  double lt = 0, rt = 1e18;
  while (rt - lt > 1e-8) {
    double mid = (lt + rt) / 2;
    if (ok(mid))
      rt = mid;
    else
      lt = mid;
  }
  cout << setprecision(15) << lt << endl;
  return 0;
}
