At each of the points \((8, 8, \frac{\pi}{2}\), (\pi, \pi, \pi), (-6, 6, \frac{5\pi}{6})\), evaluate the function \(w(r, s, t) = \frac{r - s}{\sin(t)}\) or indicate that the function is undefined there.
(Use symbolic notation and fractions where needed. If the function is undefined at the given point, type UNDEFINED.)
w\left(8, 8, \frac{\pi}{2}\right) =
w(\pi, \pi, \pi) =
w\left(-6, 6, \frac{5\pi}{6}\right) =
