分类讨论思想不只广泛应用于解代数题,而且更广泛地应用于解几何题.如角的分类,三角形的分类,四边形的分类,两直线的位置关系的分类,点、直线与圆的位置关系的分类,两圆的位置关系的分类等都需要用分类讨论的思想去解决.特别是几何的有些重要定理的证明,犹如圆周角定理、弦切角定理,都充分体现了分类讨论思想的应用.在近几年的中考试题中, The idea of ​​classification and discussion is not only widely used in solving algebraic problems, but also more widely used in solving geometrical problems such as the classification of angles, the classification of triangles, the classification of quadrilaterals, the classification of the positional relationship between two lines, and the positional relationship between points, lines and circles. The classification, the classification of the positional relations of the two circles, etc. need to be solved by the idea of ​​classification and discussion. In particular, the proof of some important theorems of geometry, such as the theorem of circumferential angle, the theorem of string cut-off angle, fully reflect the application of the idea of ​​classification and discussion. In the midterm exam questions in recent years,