#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-7;
const double PI = acos(-1);
const long long INFF = (long long)1e18;
const int INF = (int)1e9;
const int mod = (int)1e9 + 7;
const int MAX = (int)1e2 + 7;
int sx, sy;
int ex, ey;
int vx, vy;
int v, m;
int v1x, v1y;
int v2x, v2y;
inline long double dis(long double px, long double py) {
  return sqrt(pow((px - ex), 2) + pow((py - ey), 2));
}
bool sol(long double t) {
  long double px, py;
  if (t <= m) {
    px = sx + t * v1x;
    py = sy + t * v1y;
    long double d = dis(px, py);
    if (d > t * v)
      return 0;
    else
      return 1;
  } else {
    px = sx + m * v1x + (t - m) * v2x;
    py = sy + m * v1y + (t - m) * v2y;
    long double d = dis(px, py);
    if (d > t * v)
      return 0;
    else
      return 1;
  }
  return 0;
}
int main(void) {
  scanf("%d %d %d %d", &sx, &sy, &ex, &ey);
  vx = ex - sx, vy = ey - sy;
  scanf("%d %d", &v, &m);
  scanf("%d %d %d %d", &v1x, &v1y, &v2x, &v2y);
  long double l = 0, r = 1e9;
  while (fabs(r - l) > eps) {
    long double mid = (l + r) / 2;
    if (sol(mid))
      r = mid;
    else
      l = mid;
  }
  printf("%.11Lf\n", l);
  return 0;
}
