#include <bits/stdc++.h>
template <typename T, typename T2>
T dist2(T x, T y, T2 x2, T2 y2) {
  return (x - x2) * (x - x2) + (y - y2) * (y - y2);
}
int main() {
  long long x1, y1, x2, y2;
  scanf("%I64d%I64d%I64d%I64d", &x1, &y1, &x2, &y2);
  x2 -= x1;
  y2 -= y1;
  long long vmax, t, vx, vy, wx, wy;
  scanf("%I64d%I64d%I64d%I64d%I64d%I64d", &vmax, &t, &vx, &vy, &wx, &wy);
  long long x = vx * t;
  long long y = vy * t;
  double l, r;
  if (dist2(x, y, x2, y2) < vmax * vmax * t * t) {
    l = 0;
    r = t;
    for (int it = 0; it < 300; it++) {
      double m = (l + r) / 2;
      if (dist2(vx * m, vy * m, x2, y2) < vmax * vmax * m * m) {
        r = m;
      } else {
        l = m;
      }
    }
  } else {
    l = t;
    r = 100000000;
    for (int it = 0; it < 300; it++) {
      double m = (l + r) / 2;
      if (dist2(vx * t + wx * (m - t), vy * t + wy * (m - t), x2, y2) <
          vmax * vmax * m * m) {
        r = m;
      } else {
        l = m;
      }
    }
  }
  printf("%.15f\n", (l + r) / 2);
}
