Use a calculating utility, where needed, to approximate the polar coordinates of the points whose rectangular coordinates are given.

NOTE: Enter your answers in the form $(r,),$ where $r>0$ and Round any non$-$integer answers to five decimal places.

$($a$)(8,15)$

$($b$)(16,-30)$

$($c$)(-8,ta{n}^{-1}(1))$