#include <bits/stdc++.h>
using namespace std;
int N, sx, sy, fx, fy, T, ax, ay, bx, by, vm;
long double eps = 0.00000000001;
int main() {
  scanf("%d%d%d%d%d%d%d%d%d%d", &sx, &sy, &fx, &fy, &vm, &T, &ax, &ay, &bx,
        &by);
  long double ret = 1000000000, st = 0, dr = 1000000000;
  while (dr - st >= eps) {
    long double mij = (st + dr) / 2;
    long double x, y;
    if (mij <= T) {
      x = sx + ax * mij;
      y = sy + ay * mij;
    } else {
      x = sx + ax * T + bx * (mij - T);
      y = sy + ay * T + by * (mij - T);
    }
    if (sqrt((x - fx) * (x - fx) + (y - fy) * (y - fy)) / mij <= vm) {
      ret = mij;
      dr = mij - eps;
    } else {
      st = mij + eps;
    }
  }
  double rez = ret;
  printf("%.12lf", rez);
  return 0;
}
