Originally Posted by

**SkyWolf** Thanks both, i already looked into wolfram way before posting here, but the solution there calls for $\displaystyle tanh^{-1}$ (hyperbolic tangent?) which is something we didn't touched at all in my math course (which is the at the one in first year so no previous ones). So, there must be something odd with all this.

If it can help understanding where the issue is, i'll post the initial form of the integral before substitutions:

$\displaystyle \int \frac{(cosx-(cosx)^3)}{(1+2(cosx)^2)}$

So.. How come i have to complete this integral without even knowning about $\displaystyle tanh^{-1}$? It is doable elseway?

Thanks in advance,

SkyWolf