Do you have to use CA?.
You should get
They involve arctan
The order of these poles is 1.
For a pole of order 1 of a function f, find this limit :
and it'll give the residue.
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More generally... :
A singularity is a pole of a function f if there exists a positive integer n, such that :
, where A is a finite value. (n will be the order)
Then there is a direct formula giving the residue :