一、课题课题是一节课的核心，是教学重点内容的高度概括．教师在一节新课中，首先处理好课题是上好一节素质教育课的起点．1．弦切角的地位和作用．弦切角是直线与圆特殊位置关系下产生的，它是继圆周角后又一个重要内容．随着学生知识容量的增加，仅从圆周角理论研究和解决问 1. The topic is the core of a class and is a high-level summary of the teaching content. In a new class, teachers first deal with the topic is the beginning of a good part of quality education class. 1. Chord angle position and role. The chord angle is produced by the special relationship between the straight line and the circle. It is another important content after the circle angle. With the increase of students’ knowledge capacity, only from the study and solution of the theory of the circumference angle