We contruct a new triangle as shown.
Angle $x$ is equal to $90^\circ - (90^\circ - y) = y$, so the
highlighted triangles are similar. Therefore $$p = 48 \times
\frac{39}{52} = 36$$ $$q =20\times \frac{39}{52} = 15$$

The base is split $48 - q : q = 33 : 15 = 11 : 5$ and the ball falls a distance of $p + 20 = 36 + 20 = 56$.