Domain is what goes in,
Range is what comes out
For inverse functions
x goes in, and angle comes out.
So, domain is all possible values of x
and range is all possible values of angles
Domain and Range of Trigonometry Functions
Domain 
Range 

sin ^{ 1 } 
[–1, 1] 
[π/2,π/2] 
cos ^{ 1 } 
[–1, 1] 
[0,π] 
tan ^{ 1 } 
R 
(π/2,π/2) 
cosec ^{ 1 } 
R – (–1, 1) 
[π/2,π/2]  {0} 
sec ^{ 1 } 
R – (–1, 1) 
[0,π]{π/2} 
cot ^{ 1 } 
R 
(0,π) 