Consider the integral sin(y)cos(y)+7 dy\displaystyle \int\frac{{-{\sin{{\left({y}\right)}}}}}{{{\cos{{\left({y}\right)}}}+{7}}}\ {\left.{d}{y}\right.}:

This can be transformed into a basic integral by letting

u=\displaystyle {u}=   and

du=\displaystyle {d}{u}= dy\displaystyle {\left.{d}{y}\right.}  

After performing the substitution, you obtain the integral

\displaystyle \int du\displaystyle {d}{u}