#include <bits/stdc++.h>
using namespace std;
long long mod = (1000000007LL);
inline long long Mod(long long a, long long b) { return (a % b); }
inline long long poww(long long a, long long b) {
  long long res = 1;
  while (b > 0) {
    if (b & 1) res = (res * a) % mod;
    a = (a * a) % mod;
    b >>= 1;
  }
  return res;
}
long long gcd(long long a, long long b) {
  while (b) {
    a %= b, swap(a, b);
  }
  return a;
}
void read(vector<int> &w, int n) {
  w.resize(n);
  for (int i = 0; i < n; i++) cin >> w[i];
}
void print(vector<int> &w) {
  for (int i = 0; i < (int)(w).size(); i++) {
    if (i == (int)(w).size() - 1)
      cout << w[i] << "\n";
    else
      cout << w[i] << " ";
  }
}
int prodmod(vector<int> w);
int summod(vector<int> w);
int n, m, q, k, v[300050], ans;
pair<int, int> w[300050];
string second;
double x1, x2, y11, y2, vmax, t, vx, vy, wx, wy;
int32_t main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> x1 >> y11 >> x2 >> y2;
  cin >> vmax >> t >> vx >> vy >> wx >> wy;
  auto check = [&](double x) {
    double xi = x1 + vx * min(x, t) + wx * max(0.0, x - t);
    double yi = y11 + vy * min(x, t) + wy * max(0.0, x - t);
    double dist = sqrt((x2 - xi) * (x2 - xi) + (y2 - yi) * (y2 - yi));
    if (dist <= vmax * x) return 1;
    return 0;
  };
  double ini = 0, fim = (1e15), mid;
  for (int cnt = 0; cnt < 100; cnt++) {
    mid = (ini + fim) / 2.0;
    if (check(mid))
      fim = mid;
    else
      ini = mid;
  }
  cout << setprecision(10) << fixed << (ini + fim) / 2.0 << "\n";
}
int summod(vector<int> w) {
  int curr = 0;
  for (int i = 0; i < (int)(w).size(); i++) {
    curr = (curr + w[i]) % mod;
    if (curr < 0) curr += mod;
  }
  return curr;
}
int prodmod(vector<int> w) {
  int curr = 1;
  for (int i = 0; i < (int)(w).size(); i++) {
    if (w[i] >= mod) w[i] %= mod;
    curr = (curr * w[i]) % mod;
    if (curr < 0) curr += mod;
  }
  return curr;
}
