/question/276043239 . html；

Referring to the answer to the above question, we can get the idea of this question. Vision:

Rotate the triangle PBC 60 degrees counterclockwise around point C to triangle P'B'C, so PC is converted into PP', PB is converted into P'B', and the minimum value of PA+PB+PC is calculated to find the length of AB' (Note: since triangle BB'C is an equilateral triangle after reconnecting BB', the length of AB' is constant.

The reason for this: Generally speaking, the problem of finding the minimum sum of line segments in geometry problems is based on the most primitive theoretical basis of "the shortest line segment between two points", just like qq20235039 on the second floor said, "Generally speaking, there is no clue to the geometry problems in junior high schools? Making an equilateral triangle can solve many problems. "