Moving-Cluster method for determination of the distance of Hyades. A starter problem
The angle you are looking for
$$\cos \theta = \sin \delta_1 \sin \delta_2 + \cos \delta_1 \cos \delta_2 \cos (a_1-a_2),$$
where $(a_1, \delta_1)$ are the RA and Dec of the star and $(a_2,\delta_2)$ the RA and Dec of the convergent point.