25．（2023春•当涂县校级期中）已知函数$f(x)=\cos (\omega x+\frac{\pi }{3})(\omega >0)$在区间$[\frac{\pi }{4},\frac{3}{4}\pi ]$上单调递减，则实数$\omega$的取值范围为 ___$(0$[，]$\frac{8}{9}]$___．