#include <bits/stdc++.h>
using namespace std;
double v;
double Time(double X1, double Y1, double X2, double Y2) {
  return sqrt((X1 - X2) * (X1 - X2) + (Y1 - Y2) * (Y1 - Y2)) / v;
}
int main() {
  double c1, c2, r1, r2, t, vx, vy, wx, wy, l, r, mid;
  int i;
  cin >> c1 >> r1 >> c2 >> r2 >> v >> t >> vx >> vy >> wx >> wy;
  if (Time(c1 + vx * t, r1 + vy * t, c2, r2) <= t) {
    l = 0, r = t;
    for (i = 1; i <= 200; i++) {
      mid = (r + l) / 2;
      if (Time(c1 + vx * mid, r1 + vy * mid, c2, r2) < mid)
        r = mid;
      else
        l = mid;
    }
    printf("%.12f\n", (double)mid);
  } else {
    l = t, r = 1e15;
    for (i = 1; i <= 200; i++) {
      mid = (r + l) / 2;
      if (Time(c1 + vx * t + wx * (mid - t), r1 + vy * t + wy * (mid - t), c2,
               r2) < mid)
        r = mid;
      else
        l = mid;
    }
    printf("%.12f\n", (double)mid);
  }
  return 0;
}
