8. (2007 Shanghai College Entrance Examination) The smallest positive period of the function $y=\sin \left(x+\frac{\pi}{3}\right) \sin \left(x+\frac{\pi}{2}\right)$ is $\qquad$.
8. $\pi$. The given function is transformed into $y=-\frac{1}{2}\left[\cos \left(2 x+\frac{5}{6} \pi\right)-\cos \frac{\pi}{6}\right]$, so its smallest positive period is $T=\frac{2 \pi}{2}=\pi$.