the domain of sin -1 x is [-1,1]
sec x lies between [-infinity,-1] union [1,infinity]
sec x is equal to -1 at (2n+1)
,so [sec x]=-1 at this value
[sec x] =1 means sec x lies between [1,2)
that happens when x lies between [0,
/3) ,general eq. is [2n
,2n
+-
/3)
so the final answer is (2n+1)
union [2n
,2n
+-
/3)