Let f(x)=sec−1([1+sin2x]);  where [.] denotes greatest integer function. Then the set of points where f(x) is not continuous is

f(nπ+)=sec−11=0  and f(nπ−)=sec−11=0  and f(nπ)=0 ∴f  is continuous at x=nπ f((2n−1)π2+)=sec−11=0  but f((2n−1)π2)=sec−12=π3 ∴f  is discontinuous at x=(2n−1)π2  for all n∈I