#include <bits/stdc++.h>
using namespace std;
int d1[4][2] = {{1, 0}, {0, 1}, {0, -1}, {-1, 0}};
int d2[8][2] = {{1, 0}, {0, 1},  {0, -1}, {-1, 0},
                {1, 1}, {-1, 1}, {1, -1}, {-1, -1}};
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cout << setprecision(10) << fixed;
  double x1, y1, x2, y2;
  double vmax, t;
  double vx, vy, wx, wy;
  cin >> x1 >> y1 >> x2 >> y2 >> vmax >> t >> vx >> vy >> wx >> wy;
  double l = 0, r = 10e9;
  for (int i = 0; i < 101; ++i) {
    double mid = (l + r) * 0.5;
    double nx = x1 + min(t, mid) * (vx) + max(mid - t, 0.0) * wx;
    double ny = y1 + min(t, mid) * (vy) + max(mid - t, 0.0) * wy;
    double len = hypot(nx - x2, ny - y2);
    if (len < mid * vmax) {
      r = mid;
    } else {
      l = mid;
    }
  }
  cout << r << "\n";
  return 0;
}
