Consider the following. $($If an answer does not exist, enter DNE.$)$

f$($x$)=7$ sin$($x$)+7$ cos$($x$),0$ x $2$

$($a$)$

Find the interval$($s$)$ on which f is increasing. $($Enter your answer using interval notation.$)$

$($b$)$

Find the interval$($s$)$ on which f is decreasing. $($Enter your answer using interval notation.$)$