Two classes. "Basic Theorem of Plane Vector and Coordinate Operation" is the teaching content of the third section of chapter 2 of compulsory mathematics 4 in senior high school of People's Education Press, with a total of 2 class hours. In actual teaching, many teachers do not put the study of the basic theorem of plane vector at the center of teaching. After describing the theorem directly, they will soon turn the teaching "center of gravity" to coordinate representation and operation.