Rabbit can stay opposite the agent while backing up

The agent, if logical, will reverse direction if that reversal will reduce the distance between the agent and where a line through the agent and rabbit hits the shore opposite the agent. For example, if the agent runs 4x as fast as the rabbit, the rabbit can swim directly away from the agent then return to a point directly opposite the agent just as the agent completes a 60º arc of the circle. At this point, the rabbit crosses this 60º line, so the agent reverses direction. This move can be repeated but is less effective each time.