# Using Integration Techniques, when is it appropriate to use inverse trig and natural logs?

I'm currently learning integration techniques, and I often run into a problem; when i'm solving an integral, sometimes I need to use the natural log simplification and other times I need to use one of the inverse trig formulas, namely arctangent. I've done plenty of reading before I came here on when to use ln vs arctan, and perhaps my wording isn't correct(if so I apologize for that), but I haven't found any answers. Hopefully some of you fine folks can clarify things for me as my professor won't answer my emails.

For the following problem, i'm using the integration by parts technique:

$$\int{\arctan x} {\;dx} = x\;\arctan\;x \;- \int{\frac{x}{x^2\;+1}}\;dx$$