Q$7.(10$ marks$)$ The following f $($x$)$ is a periodic function of period T $=2\backslash$pi $,$ defined over the

period $\backslash$pi $<=$ x $<=\backslash$pi $.$

f $($x$)=$

$\{0$ when $\backslash$pi $<=$ x $<=0$

$\backslash$pi $$ x when $0<$ x $<=\backslash$pi $,$ of period T $=2\backslash$pi $.$

Express f $($x$)$ as a Fourier series expansion. Showing result only without reasoning or argumentation

will be insufficient.