How to find the original function of 1 divided by 1 -- (the square of cosx) dcoxx

How to find the original function of 1 divided by 1 -- (the square of cosx) dcoxx

Let t = cosx,
Then ∫ 1 / (1-T ^ 2) DT
=1/2∫[1/(1+t)+1/(1-t)]dt
=1/2[ln│1+t│-ln│1-t│]+C
=1/2[ln│1+cosx│-ln│1-cosx│]+C