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数学竞赛题对考生的能力要求较高,因而题目显得很难,很多考生往往觉得难于下手。其实,仔细分析,竞赛題中的很多题目都是由一些基本题通过组合、引伸、推广等变化而得到的,因而往往能从课本中找到它们的“影子”。本文选用部分竞赛题为例,以说明之。例1 在△ABC中,BC边上的高AD=12,△A的平分线AE=13。设BC边上的中线
The problem of mathematics contest has higher requirements on the ability of candidates, so the topic seems difficult, and many candidates often find it difficult to start. In fact, careful analysis shows that many topics in competition questions are derived from changes in basic questions such as composition, extension, and promotion. Therefore, they often find their “shadows” in textbooks. This article selects part of the contest as an example to illustrate it. Example 1 In ΔABC, the high AD on the BC side was equal to 12, and the bisector AE of ΔA was equal to 13. Set the median line on the BC side