Answer
$\tan^{-1}(\ln t)+c.$
Work Step by Step
Since $ u=\ln t $, then $ du=\frac{1}{t}dt $.
Now, we have
$$\int \frac{dt}{t(1+(\ln t)^2)}dt =\int \frac{1}{1+u^2}du\\
=\tan^{-1}u+c=\tan^{-1}(\ln t)+c.$$
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