Big-O, Big-Omega, Θ notation

Since 5 + 2sin(n) is bounded by a constant value both above a below, it holds that 5 + 2sin(n) = O(1). It also holds that it is Ω(1). Since it is both, it is also Θ(1).

You can show this more formally by finding the values between which your function is bounded, and using the definitions of Big-O and Big-Omega.