A direct shot in the far right corner

In a simulation of a pool game, the pool table is a rectangle with a horizontal width of 15 units and a vertical length of 30 units.

The left bottom corner of this rectangle is at the origin of an $xy$ reference frame with standard orientation. You have two billiard balls of radius 1 unit, the first is the cue ball (drawn in light green) and is placed at $(6,11)$ , the second is the target ball and is placed at $(9, 19)$ . You want to shoot the cue ball (green) in a certain direction, such that it collides with the target ball, causing it to move to the target point which, in this problem, is the far right corner, whose coordinates are $(15, 30)$ . Find the angle $\theta$ that the direction of your shot of the cue ball makes with the positive $x$ -axis, in radians , and report $\lfloor 1000 \hspace{4pt} \theta \rfloor$ .