Seven types of shortest path problems include: translation shortest problem, symmetry shortest problem, vertical line shortest problem, step shortest problem, cylinder shortest problem, cuboid shortest problem and cube shortest problem.

Typical questions and problem-solving skills of the shortest path problem in junior middle school mathematics. The key is that we are good at making a symmetrical point of a fixed point about the straight line where the moving point is located, or using translation and expansion diagrams to deal with it.

The shortest line segment between two points, from A to B, must be the shortest straight line distance. In specular reflection, the incident angle is equal to the exit angle.