A billiard ball lies on a table in the shape of an acute angle. How
should you hit the ball so that it returns to its starting location
after hitting each of the two banks once? Is it always possible to do
so?
(When the ball hits the bank, it bounces. The way it bounces is
determined by the shortest path rule – if it begins at some point \(D\) and ends at some point \(D'\) after bouncing, the path it takes
is the shortest possible path that includes the bounce.)