Incline Plane Coefficient Of Friction Proof

$F_{net}=mg\sin \theta -mg\cos \theta \mu$ $ma=mg\sin \theta -mg\cos \theta \mu$ $a=g\sin \theta -g\cos \theta \mu$ If we assume a ~ 0, where it moves but acceleration is almost 0, $0=g\sin \theta -g\cos \theta \mu$ $0=\sin \theta -\cos \theta \mu$ $-\sin \theta =-\cos \theta \mu$ $\tan \theta =\mu$