论文部分内容阅读
圆的切线是圆的重要内容之一,它具有承前启后的作用．它不仅与前几节的垂径定理、圆心角定理、圆周角定理、圆内接四边形性质紧密联系,还为后面学习内切圆、切线长定理、切割线定理、两圆相切等知识打基础,又是切线相关知识的延伸和补充,是考试命题不可缺少的内容,是九年级学生必须掌握的基础知识和技能．下面归纳出证明切线的三种常见方法,供同学们学习参考．
The round tangent is one of the important contents of the circle. It has the function of inheriting the past. It is not only closely related to the previous chapters’ vertical theorem, central angle theorem, circumferential angle theorem and circular inscribed quadrilateral, but also used to learn the inscribed circle, the tangent length theorem, the cutting line theorem, and the two-circle tangent. The foundation is an extension and supplement of tangent-related knowledge. It is an indispensable part of the examination proposition. It is the basic knowledge and skills that ninth-grade students must master. The three common methods for demonstrating tangents are summarized below for students’ reference.