$I=\int \dfrac{\ln (\tan x)}{2\sin x \cos x}dx$ đặt $\ln (\tan x) = t \Rightarrow \dfrac{1}{\sin x \cos x }dx=dt$
$I=\dfrac{1}{2}\int \limits_{\ln\frac{1}{\sqrt 3}}^{\ln \sqrt 3} tdt =\dfrac{1}{4}t^2 \bigg |_{\ln\frac{1}{\sqrt 3}}^{\ln \sqrt 3}$
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