#include <bits/stdc++.h>
using namespace std;
bool canReach(double x1, double y1, double x2, double y2, double vx, double vy,
              double wx, double wy, double vmax, double timeChange, double t) {
  double px = x1;
  double py = y1;
  if (t <= timeChange) {
    px += (t * vx);
    py += (t * vy);
  } else {
    px += (timeChange * vx);
    py += (timeChange * vy);
    px += (t - timeChange) * wx;
    py += (t - timeChange) * wy;
  }
  double distance = sqrt((x2 - px) * (x2 - px) + (y2 - py) * (y2 - py));
  return (distance <= vmax * t);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  ;
  double x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  double vmax, timeChange;
  cin >> vmax >> timeChange;
  double vx, vy, wx, wy;
  cin >> vx >> vy >> wx >> wy;
  double yes = 1000000000, no = 0;
  if (canReach(x1, y1, x2, y2, vx, vy, wx, wy, vmax, timeChange, timeChange)) {
    yes = timeChange;
  } else {
    no = timeChange;
  }
  while (yes - no > 10e-9) {
    double t = (yes + no) / 2;
    if (canReach(x1, y1, x2, y2, vx, vy, wx, wy, vmax, timeChange, t)) {
      yes = t;
    } else {
      no = t;
    }
  }
  cout << fixed << setprecision(10) << yes << endl;
  return 0;
}
