To solve the problem, I followed the following steps:
Is it possible to find a closed form for $x$?
$$\frac{\sin(x)}{\sin(\beta-x)}=\frac{\sin(\alpha)\,\sin(\theta-\gamma)}{\sin(\gamma)\,\sin(\theta-\alpha)}$$
where, $$x:= \angle OBC,\beta:=\angle ABC ,\alpha:=\angle OAC, \gamma:=\angle OCA ,\theta:=\angle BAC=\angle ACB$$
Mathematica says that,
$x\approx 0.033921 \approx 1.94353^\circ\,$
Is there another method to find $x$?

If everything except $x$ is known, $$ \frac{\sin(x)}{\sin(\beta-x)}=c$$ reduces to $$ \tan(x) = \frac{c \sin(\beta)}{1+ c \cos(\beta)}$$