Find the range of f(x)=sinx2+cosxf(x) = \frac{\sin x}{2 + \cos x}f(x)=2+cosxsinx for x∈Rx \in \mathbb{R}x∈R.
[−13,13][-\frac{1}{3}, \frac{1}{3}][−31,31]
[−33,33][-\frac{\sqrt{3}}{3}, \frac{\sqrt{3}}{3}][−33,33]
[−12,12][-\frac{1}{2}, \frac{1}{2}][−21,21]
[−1,1][-1, 1][−1,1]