Ex $5\mathrm{.}16($mod$)$: The bent bar ABCD is in the $x-y$ plane and is supported by a ball$-$in$-$socket joint at $A,$ a special journal bearing at $B($that resists translation in the $x$ and $z$ directions only $-$ it does not resist translation in $y$ and it does not resist any rotations$),$ and a roller at $C.$

There is a vertical force of $900N$ and a $200Nm$ couple moment whose coordinate direction angles are $=120,=120,=45$

$($a$)$ List the decoupled equations of equilibrium to determine each of the support reactions $($e$.$g$.{\displaystyle \underset{?}{\overset{?}{}}}{M}_{PQ}=0$ finds $R_y)$

$($b$)$ Determine the reactions at A using the decoupled equations of equilibrium listed above $($there is no need to find the reactions at $B$ and $C)$