在讲授椭圆后,经常有学生问这样的问题:椭圆的最大弦长是否是椭圆的长轴长?问题看起来非常显然,但如何证明,教材及教参上没有说明,许多资料上也没有这方面的记录,笔者曾对这个问题作了些探索也得出过几种证法,其中用向量证明这个问题尤为简单,下面写出来供参考.设F1,F2是椭圆的 After teaching ellipses, students often ask questions such as: Is the maximum length of the ellipse the long axis of the ellipse? The question may seem obvious, but how to prove that there is no explanation on teaching materials and teaching materials and many materials do not have this aspect The author has made some exploration on this issue has also come up with several kinds of card law, in which the vector to prove this problem is particularly simple, the following written for reference. Let F1, F2 is elliptical