#include <bits/stdc++.h>
using namespace std;
double x0, yy0, x1, yy1, vmax, t, vx, vy, wx, wy;
double dis(double x, double y, double a, double b) {
  return ((x - a) * (x - a) + (y - b) * (y - b));
}
bool panduan(double time) {
  double xx, yy, d;
  if (time < t) {
    xx = x0 + vx * time;
    yy = yy0 + vy * time;
  } else {
    xx = x0 + vx * t + wx * (time - t);
    yy = yy0 + vy * t + wy * (time - t);
  }
  if (dis(xx, yy, x1, yy1) < vmax * vmax * time * time)
    return true;
  else
    return false;
}
int main() {
  cin >> x0 >> yy0 >> x1 >> yy1 >> vmax >> t >> vx >> vy >> wx >> wy;
  double mid, l, r, s;
  l = 0;
  r = 1e10;
  mid = (l + r) / 2;
  s = r - l;
  while (s > 1e-8) {
    mid = (l + r) / 2;
    if (panduan(mid))
      r = mid;
    else
      l = mid;
    s = r - l;
  }
  printf("%.18f\n", mid);
  return 0;
}
