The correct option is C 5
sinx+cosx=√2(cosπ4sinx+sinπ4cosx)=√2sin(x+π4)
Thus, f(x)=[√2sin(x+π4)]
We know, [x] is not continuous where x is integer
Hence f will not be continuous where √2sin(x+π4) will be an integer.
Hence points of discontinuities in the given interval are,
x=π2,3π4,π,3π2,7π4