#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:256000000")
using namespace std;
int x1, yy1, x2, y2;
int vx, vy, wx, wy;
int vMax, tFoo;
bool can(double t) {
  double x, y;
  if (t <= tFoo) {
    x = x2 + (-vx) * t;
    y = y2 + (-vy) * t;
  } else {
    x = x2 + (-vx) * tFoo + (-wx) * (t - tFoo);
    y = y2 + (-vy) * tFoo + (-wy) * (t - tFoo);
  }
  double dist = sqrt((x - x1) * (x - x1) + (y - yy1) * (y - yy1));
  return (dist / vMax < t);
}
int main() {
  cout.precision(30);
  cin >> x1 >> yy1 >> x2 >> y2;
  cin >> vMax >> tFoo;
  cin >> vx >> vy >> wx >> wy;
  double l = 0, r = 1e9;
  for (int i = 0; i < 100; i++) {
    double m = (l + r) / 2;
    if (can(m)) {
      r = m;
    } else
      l = m;
  }
  cout << l << endl;
  return 0;
}
