Integrating $\int \log(\tan(2x)) dx$
Sebastian Wright
Looking online I see that people are integrating $\int \tan(2x)dx$ by replacing $\tan(2x)$ with $\frac{\sin(2x)}{\cos(2x)}$ and then using $u$-substitution for $2x$. Why can you not simply use $u=2x$ and then integrate $\frac12\int \tan(u)du$?
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$\begingroup$That's perfectly fine as long as you can find an antiderivative.
$\endgroup$ $\begingroup$It is correct, your answer should be $\frac 12 \ln|\sec 2x| +C$.
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