Indefinite integral of $\cos^{3}(x) \cdot \ln(\sin(x))$ I need help. I have to integrate $\cos^{3} \cdot \ln(\sin(x))$ and I don´t know how to solve it.  In our book it is that we have to solve using the substitution method. If somebody knows it, you will help me..please 

If you mean $\cos^3 x\ln(\sin x)$, let $u=\sin x$. Then $du=\cos x dx$, and $$\begin{align*}
\cos^3 x\ln(\sin x)dx&=\cos^2 x\ln(\sin x)\Big(\cos x dx\Big)\\
&=\cos^2 x\ln u \,du\\
&=(1-\sin^2 x)\ln u\,du\\
&=(1-u^2)\ln u\,du\;,
\end{align*}$$
which can be integrated by parts.
