#include <bits/stdc++.h>
using namespace std;
int vMax;
int t;
int x1, y234, x2, y2;
int vx, vy;
int wx, wy;
bool check(double tm) {
  if (tm <= t) {
    double x3 = x1 + vx * tm;
    double y3 = y234 + vy * tm;
    return (x3 - x2) * (x3 - x2) + (y3 - y2) * (y3 - y2) <=
           tm * tm * vMax * vMax;
  } else {
    double x3 = x1 + vx * t + wx * (tm - t);
    double y3 = y234 + vy * t + wy * (tm - t);
    return (x3 - x2) * (x3 - x2) + (y3 - y2) * (y3 - y2) <=
           tm * tm * vMax * vMax;
  }
}
int main() {
  scanf("%d", &x1), scanf("%d", &y234), scanf("%d", &x2), scanf("%d", &y2);
  scanf("%d", &vMax), scanf("%d", &t);
  scanf("%d", &vx), scanf("%d", &vy);
  scanf("%d", &wx), scanf("%d", &wy);
  double lb = 0, rb = 1e9;
  for (int iter = 0; iter < 100; ++iter) {
    double tm = (lb + rb) * 0.5;
    if (check(tm))
      rb = tm;
    else
      lb = tm;
  }
  printf("%.20lf\n", lb);
  return 0;
}
