化简: $\left(\tan x+\frac{1}{\tan x}\right) \sin ^{2} x=$
$\left(\tan x+\frac{1}{\tan x}\right)_{\sin ^{2} x=}\left(\frac{\sin x}{\cos x}+\frac{\cos x}{\sin x}\right) \sin ^{2} x=\left(\frac{\sin ^{2} x+\cos ^{2} x}{\sin x \cos x}\right) \sin ^{2} x=\frac{\sin x}{\cos x}=\tan x$.