#include <bits/stdc++.h>
using namespace std;
bool Check(long double dx, long double dy, long double l) {
  return dx * dx + dy * dy <= l * l;
}
int main() {
  int x1, y1, x2, y2, v, t, vx, vy, wx, wy;
  cin >> x1 >> y1 >> x2 >> y2 >> v >> t >> vx >> vy >> wx >> wy;
  long double st = 0, ed = t, mid;
  bool ok = false;
  for (int i = 0; i < (500); i++) {
    mid = (st + ed) * 0.5;
    long double xx = x1 + vx * mid, yy = y1 + vy * mid;
    if (Check(xx - x2, yy - y2, v * mid)) {
      ed = mid;
      ok = true;
    } else {
      st = mid;
    }
  }
  if (ok) {
    printf("%.10f\n", (double)st);
    return 0;
  }
  st = t, ed = 1e8;
  for (int i = 0; i < (500); i++) {
    mid = (st + ed) * 0.5;
    long double xx = x1 + vx * t + wx * (mid - t),
                yy = y1 + vy * t + wy * (mid - t);
    if (Check(xx - x2, yy - y2, v * mid)) {
      ed = mid;
      ok = true;
    } else {
      st = mid;
    }
  }
  assert(ok);
  printf("%.10f\n", (double)st);
  return 0;
}
