#include <bits/stdc++.h>
using namespace std;
double x1, hz, x2, y2, vx, vy, wx, wy, vmax, t;
bool can(double tm) {
  double x = x1;
  double y = hz;
  if (tm <= t) {
    x += vx * tm;
    y += vy * tm;
  } else {
    x += vx * t + wx * (tm - t);
    y += vy * t + wy * (tm - t);
  }
  return (x - x2) * (x - x2) + (y - y2) * (y - y2) <
         tm * tm * vmax * vmax + 1e-9;
}
int main() {
  cin >> x1 >> hz >> x2 >> y2;
  cin >> vmax >> t;
  cin >> vx >> vy >> wx >> wy;
  double l = 0, r = 1e9;
  for (int it = 0; it < (int)(200); it++) {
    double mid = (l + r) / 2;
    if (can(mid))
      r = mid;
    else
      l = mid;
  }
  cout.precision(15);
  cout << fixed << r << endl;
  return 0;
}
