#include <bits/stdc++.h>
using namespace std;
double vlen(double x, double y) { return x * x + y * y; }
double x, y, xx, yy, v, t, vx, vy, wx, wy;
pair<double, double> f(double T) {
  if (T == 0.0) return {v + 1.0, v + 1.0};
  double gox = x / T + (min(T, t) / T) * vx + (max(0.0, T - t) / T) * wx;
  double goy = y / T + (min(T, t) / T) * vy + (max(0.0, T - t) / T) * wy;
  double nx = xx / T - gox, ny = yy / T - goy;
  return {nx, ny};
}
int main() {
  cin >> x >> y >> xx >> yy;
  cin >> v >> t;
  cin >> vx >> vy >> wx >> wy;
  double l = 0.0, r = 1e9;
  for (int iter = 0; iter < 300; ++iter) {
    double T = (l + r) / 2.0;
    pair<double, double> cur = f(T);
    if (vlen(cur.first, cur.second) <= v * v)
      r = T;
    else
      l = T;
  }
  cout << setprecision(30) << r << '\n';
  return 0;
}
