Mathematical circle is also a very important knowledge point. Today, let's summarize some knowledge points of circle in primary school ~

π is an infinite acyclic decimal with the range of 3. 1415926 ~ 3.1415927, which is generally calculated as 3.14. There are some error-prone knowledge points about the circle, and it is wrong to remember the concept clearly. For example, any two radii can form a diameter. The line segment passing through the center of the circle with both ends on the circle is called the diameter.