Answer with explanation:
The given expression is:

Domain of Cosec theta,will be all values in Radian or degree except at the point where,
→sine(theta)≠ 0.
If theta is in either Degrees or in Radian, then

The value of theta which is not in the domain for the validity of

is, →→Theta(Ф)≠ k π, for any integer ,k.