LHS
= [xcsc(x) + 1]/[xcsc(x)]
= xcsc(x)/[xcsc(x)] + 1/[xcsc(x)]
= 1 + sin(x)/x
= RHS, for x ≠ kπ for any integer k
It is an identity only subject to the exclusion that I added. It cannot be an identity anywhere csc(x) is undefined, and we can brook no division by zero.