Li Zhou, Do dogs play with rulers and compasses?
Forum Geometricorum, 15 (2015) 159--164.

Abstract. A dog runs at the speed of 1 and swims at the speed of s<1. If the dog is at point A on the shoreline and tries to get to a ball in water at point B in the least time, what path should the dog take? In this article we discuss geometric solutions to this optimization problem and its variations.

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