《中小学数学》(初中版)2014年第4期刊载了陈国玉老师撰写的《巧用口诀,妙解切线问题》一文.文章用十八字口诀,将与切线有关的问题进行了高度浓缩.学习后受益匪浅.在平时教学过程中,笔者感觉到学生对切线的性质与判定理解不清晰,使用起来经常混淆.尝试着与学生一起,辨析异同,小结方法,整理口诀,积累经验,形成能力.现提供教学片断,供参考. “Elementary and middle school mathematics” (junior high school edition) in 2014 the fourth issue of Chen Guoyu teacher wrote “clever use of formulas, clever solution tangent problem.” The article with eighteen word formulas, and tangents-related issues were highly concentrated In the usual teaching process, the author felt that the students’ understanding of the nature and judgment of the tangents is not clear and often confused to use.Try to work with students to identify similarities and differences, summarize the methods, organize formulas, accumulate experience, Forming ability. Now provide teaching pieces, for reference.