#include <bits/stdc++.h>
using namespace std;
const int MOD(1000000007);
const int INF((1 << 30) - 1);
const int MAXN();
double dis(double dx, double dy) { return sqrt(dx * dx + dy * dy); }
int main() {
  double x1, y1, x2, y2, v, t, vx, vy, wx, wy;
  scanf("%lf%lf%lf%lf%lf%lf%lf%lf%lf%lf", &x1, &y1, &x2, &y2, &v, &t, &vx, &vy,
        &wx, &wy);
  double low = 0.0, high = 1e9, mid, x, y;
  for (int i = 0; i < 100; i++) {
    mid = (low + high) / 2.0;
    x = x1 + vx * min(mid, t) + wx * max(mid - t, 0.0);
    y = y1 + vy * min(mid, t) + wy * max(mid - t, 0.0);
    if (dis(x - x2, y - y2) <= v * mid)
      high = mid;
    else
      low = mid;
  }
  printf("%.10lf", low);
}
