Which value of theta is not in the domain of validity for csc theta = 1/sin theta

Verify each identity give the domain of validity for each identity. It is very used to prove these identities for any value of theta in the domain. So I just specify the domain and leave verification for you to do t with standard values or on calculator. Because verification is an endless process. Proof is not. As proof seems to be simple I will do that which will amount to verification as well