$5\mathrm{.}2$ A system with $m=0\mathrm{.}010kg,s=36N{m}^{-1}$ and $b=0\mathrm{.}50kg{s}^{-1}$ is driven by a harmonically varying force of amplitude $3\mathrm{.}6$ N $.$ Find the amplitude A and the phase constant $$ of the steady$-$state motion when the angular frequency is

$($a$)8\mathrm{.}0s^{-1},($b$)$

$($b$)80s^{-1},$ and $($c$)800s^{-1}.$