#include <bits/stdc++.h>
using namespace std;
double X1, Y1, X2, Y2;
double vx, vy;
double wx, wy;
double v, t;
double sqr(double x) { return x * x; }
double dis(double X1, double Y1, double X2, double Y2) {
  return sqr(X1 - X2) + sqr(Y1 - Y2);
}
bool ok(double x) {
  double tmpx, tmpy;
  if (x > t) {
    tmpx = X1 + vx * t + wx * (x - t);
    tmpy = Y1 + vy * t + wy * (x - t);
  } else {
    tmpx = X1 + vx * x;
    tmpy = Y1 + vy * x;
  }
  double d = dis(tmpx, tmpy, X2, Y2);
  if (d < sqr(v * x)) return true;
  return false;
}
int main() {
  cin >> X1 >> Y1 >> X2 >> Y2;
  cin >> v >> t;
  cin >> vx >> vy;
  cin >> wx >> wy;
  double L = 0, R = 1e30;
  int bi_cnt = 0;
  while (bi_cnt < 1e6) {
    double mid = (L + R) / 2;
    if (ok(mid))
      R = mid;
    else
      L = mid;
    ++bi_cnt;
  }
  printf("%.12f\n", R);
  return 0;
}
