论文部分内容阅读
圆的切线的判定是中考命题的热点和重点,如何迅速、快捷地证明圆的切线呢?本文通过例题介绍三种常用的证明策略和方法,供参考.一、若直线经过半径的外端,则证直线垂直于半径.简记为“已知半径,证垂直”.例1如图1,半圆O为△ABC的外接半圆,AC为直径,D为劣弧BC上的一动点,P在CB的延长线上,且有∠BAP=∠BDA.
Circular tangent of the test is the hot topic and focus of the test, how to quickly and quickly prove the tangent of the circle? This paper presents three examples of commonly used proving strategies and methods for reference. First, if the straight line through the outer end of the radius, Then the straight line is perpendicular to the radius of the line, which is abbreviated as “known radius, vertical”. Example 1 As shown in Figure 1, the semicircle O is the circumscribed semicircle of △ ABC, AC is the diameter, D is the moving point on BC, P is on the extended line of CB with ∠ BAP = ∠BDA.