A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2019 Nov 26, 12:27 -0800
Dave, you wrote:
"I was sure there must be a neater answer, so I rang the author up. As soon as he said, “imagine the barn on the opposite side of the river”, it all became clear, as did the 3,4,5 triangle for distance."
Call him up again, and ask if my speculation was right that this puzzle was inspired by the optical analogy and Fermat's Principle of Least Time. :) As I say, I have never seen this puzzle before or anything similar but it jumped right out at me that it was similar to an optics problem.