11. $f(x)=\sqrt{\sin x}+\sqrt{\cos x}, x \in\left[0, \frac{\pi}{2}\right]$ The range of values is $\qquad$
11. $[1, \sqrt[4]{8}], f^{\prime}(x)=\frac{1}{2}\left(\frac{\cos x}{\sqrt{\sin x}}-\frac{\sin x}{\sqrt{\cos x}}\right)$, let $f^{\prime}(x)=0, x=\frac{\pi}{4}$, only need to compare $f(0), f\left(\frac{\pi}{2}\right)$, $f\left(\frac{\pi}{4}\right)$.