This is a mathematical theorem. It is about a teenager who once went out to study. One day, unfortunately, he learned that his old father was dying, so he hurried home at once. According to the "shortest straight line between two points", although there is a gravel field between his position A and his home B at the moment, he still set foot on the road home without hesitation. At home, as soon as the old man swallowed his breath, the young man burst into tears with regret. Neighbors told the young people that the old man kept chanting "Hu Bugui? Hu Bugui? …"

Line segment feature

(1) is limited in length and measurable;

(2) There are two endpoints;

(3) symmetry;

(4) The straight line between two points is the shortest distance between them.

Line segment attribute

Of all the straight lines connecting two points, the line segment is the shortest. It is called the shortest line segment between two points. So the sum of two sides of a triangle is greater than the third side.