Application Of Derivatives

For the function

\(f(x)=\sin x+3 x-\frac{2}{\pi}\left(x^2+x\right), \text { where } x \in\left[0, \frac{\pi}{2}\right],\)

consider the following two statements :

(I) \(f\) is increasing in \(\left(0, \frac{\pi}{2}\right)\).

(II) \(f^{\prime}\) is decreasing in \(\left(0, \frac{\pi}{2}\right)\).

Between the above two statements,