学习数学，要勤于思考，善于思考．例如，对于下面的几何题，只要我们勤于并善于从不同的角度去思考问题，就能给出多种证法．题目如图1，在ΔABC的边AB上取一点E，在CA的延长线上取一点D，使AD＝AE，且DE的延长线经过BC边的中点F．求证：BE＝CD．分析我们知道，在初二上学期的 Learn mathematics, be diligent in thinking, and good at thinking. For example, for the following geometric questions, as long as we are diligent and good at thinking from different perspectives, we can give a variety of evidence. The problem is shown in Fig. 1. Take a point E on the side AB of ΔABC, take a point D on the extension line of CA, and make AD = AE, and the extension line of DE passes the midpoint of the BC side. Proof: BE=CD. Analysis we know that in the first two semesters