We have to find the domain of y = cotx
We know that cotx = cos x / sinx
And also when sinx becomes zero cotx becomes undefined
And again we know that value of cosx and sinx can be between -1 to 1
But value of cotx can lie in between -∞ to +∞
Just for example cot30 is cos30 / sin30
= √3/2/1/2 = √3
Therefore domain of cotx is x
x ∈ R , x ≠ πn for any integer n