9. Let $\alpha, \beta, \gamma \in \left(0, \frac{\pi}{2}\right)$, and satisfy $\cos \alpha = \alpha, \cos (\sin \beta) = \beta, \sin (\cos \gamma) = \gamma$. Then the size relationship of $\alpha, \beta, \gamma$ is $\qquad$.
9. $\gamma\cos \beta$,
$$
\gamma=\sin (\cos \gamma)<\cos \gamma,
$$

and $f(x)=x-\cos x$ is an increasing function on $\left[0, \frac{\pi}{2}\right]$, then we have
$$
\gamma<\alpha<\beta .
$$