Since the curriculum reform, some teachers have always had doubts about whether to use "connection" or "connection" in junior high school mathematics. Now I want to talk about this problem. "Connecting AB" (connecting with line segments) used to be written as "Connecting AB". The First List of Variant Characters compiled by the State Language Committee on March 3, 20021day recommended the use of "connecting" or "connecting", but did not advocate the use of "connecting" or "connecting", so this set of textbooks uses "connecting" uniformly. As for the other meaning of "connection", it means that the straight line (or the circle where the arc is located) and the circle where the arc is located are tangent to a certain point and are on both sides of the radius of the tangent point (or the connecting line). This is actually a smooth connection between "lines and arcs" or "arcs and arcs". This content originally belonged to junior high school mathematics, but it was deleted from the mathematics curriculum standard published by the Ministry of Education in 200 1. In short, there were two kinds of "connections" in junior high school mathematics in the past, so the textbook writing department used to write the line segment connection as "connection" to show the difference. At present, there is only one kind of "connection" in junior middle school mathematics, and the relevant state departments also have relevant regulations on language and writing, so the textbook only uses "connection" instead of "connection" according to this regulation. The three concepts of "connection", "connection" and "connection" in junior high school geometry textbooks are often confused by students because of their similar pronunciations. Here, we compare the relations and differences between these three concepts, so that students can use them correctly. Connection and connection both refer to connecting two points with a line, but the line "connecting" two points can be a line segment, a curve, and ". There are countless ways to connect two points, but there is only one way to connect two points, especially to form a line segment. As shown in figure 1, all straight lines between point A and point B are straight lines connecting point A and point B, and only line segment AB is a straight line connecting point A and point B, so connecting two points is a special case of connecting two points, and the line segment is the shortest among the straight lines connecting two points. The difference between connection and connection is that the key is "connection", while connection and connection connect two points with lines, and the key is "connection". At the same time, the connection "Lian" is not a simple connection, but a smooth transition between the lines. There are two main types of connections. One is the connection between line segment and arc, which must meet two conditions; ① The line where the line segment is located is tangent to the circle where the arc is located (as shown in Figure 2). (2) the line segment and arc must be on both sides of the straight line where the center of the circle and the tangent point (that is, the connection point) are located; The other is the connection between arcs, which must meet two conditions: ① the circle where the arcs are located must be tangent; ② The two arcs must be on both sides of the connecting line. This situation can be divided into inner connection (the circle where the arc is tangent, as shown in Figure 3) and outer connection (the circle where the arc is tangent, as shown in Figure 4). It can be seen that the line segment is tangent to the arc, and the arc is tangent to the arc at the joint.