#include <bits/stdc++.h>
using namespace std;
const int INF = 2e9;
int mx[2];
int main() {
  int x1, y1, x2, y2, vx, vy, wx, wy, vmax, t;
  scanf("%d%d%d%d%d%d%d%d%d%d", &x1, &y1, &x2, &y2, &vmax, &t, &vx, &vy, &wx,
        &wy);
  x2 -= x1;
  y2 -= y1;
  double l = 0, r = 2e9;
  for (int iter = 200; iter--;) {
    double m = (r + l) / 2,
           a = vx * min(t * 1.0, m) + wx * max(0.0, m - t) - x2,
           b = vy * min(t * 1.0, m) + wy * max(0.0, m - t) - y2;
    if (sqrt(a * a + b * b) < vmax * m)
      r = m;
    else
      l = m;
  }
  printf("%.10f\n", r);
  return 0;
}
