在一次培优辅导过程中,我选择了如下一道平面几何题作为例题,同学们对此题很感兴趣,经过深入的思考和讨论,发现这是一道简洁优美、内涵丰富,有一定思维含量的好题,大家不仅得出了很多证明方法,还提出了新的问题.回味此题总感觉意犹未尽,于是整理如下,希望能和大家共勉.题1如图1,在☉O中,弦CD垂直于直径AB,M是OC的中点,AM的延长线交☉O于点E,DE交BC于点N.求证:BN=CN. During a training course, I chose the following example of a plane geometry as an example, the students are very interested in this issue, after in-depth thinking and discussion, I found that this is a concise and beautiful, rich in content, a certain amount of thinking Good question, we not only come up with a lot of proof methods, but also put forward new problems.Full aftertaste felt indefinable, so finishing below, I hope we can encourage each other .Table 1 Figure 1, in ☉O, the CD vertical At diameter AB, M is the midpoint of OC, and the extension of AM is ☉ O at point E, DE at BC at point N. Verification: BN = CN.