As a very important and common model in junior high school geometry, the general horse drinking model is an important question that will be examined in the regular and final questions of the senior high school entrance examination, and students must master it skillfully.

? The origin of the general drinking horses:

In ancient Rome, there was a general named Helen in Alexandria. He prefers math. Once, he wanted to go from camp A to camp B, but on the way, he wanted his horse to drink water by the river. Camp AB is located on the same side of the river, so the general will consider where to drink water in order to make the journey from Camp A to Camp B shortest.