`inttan^3x\ dx=1/2tan^2x-I_1`

Now `I_1=inttan\ x\ dx` `=-ln\ |cos x|+K`

So `inttan^3x\ dx` `=1/2tan^2x+ln\ |cos x|+K`

Note: Often in this work there is more than one way to attack the question, so it is possible to get a correct answer, but in a different form. Using math software, like Scientific Notebook, you may get:

`inttan^3x\ dx` `=1/2tan^2x-1/2ln\ |1+tan^2x|`

Are the 2 answers the same?

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