#include <bits/stdc++.h>
using namespace std;
double xx, yy, x2, y2, x3, y3;
double v, t;
double vx, vy;
double wx, wy;
double sqr(double x) { return x * x; }
double dis(double x, double y, double xx, double yy) {
  return (double)(sqr(x - xx) + sqr(y - yy));
}
bool judge(double x) {
  double tx, ty;
  if (x > t) {
    tx = xx + vx * t + wx * (x - t);
    ty = yy + vy * t + wy * (x - t);
  } else {
    tx = xx + vx * x;
    ty = yy + vy * x;
  }
  double d = dis(tx, ty, x2, y2);
  if (d < sqr(v * x)) return true;
  return false;
}
int main() {
  while (cin >> xx >> yy >> x2 >> y2) {
    cin >> v >> t;
    cin >> vx >> vy;
    cin >> wx >> wy;
    double s = 0;
    double mid, le = 0, re = 1e10;
    while (s < 1e6) {
      mid = (le + re) / 2;
      if (judge(mid))
        re = mid;
      else
        le = mid;
      s++;
    }
    printf("%.18f\n", re);
  }
  return 0;
}
