Find all singularities of $ \ \frac{z-1}{z^2 \sin z} \ $
Determine if they are isolated or nonisolated.
This is not hard, it is $z = 0$ and $z = k\pi$.
But how do I:
For isolated singularities, determine if they are removable or nonremovable and, if nonremovable, determine their order.
Do I need to expand this to a power series? If so, I have no idea where to attack...
Please help! Thanks!