平几不等式的证明难度大,方法多,确实不可一概而论,但是有很多证线段不等的题目,最关键的就是解决线段搬家的问题,只要线段搬家到位,堡垒就攻克了.下面,我们通过几个例题,来体会这种方法的实质.例1 已知 A′为△ABC 的外角平分线 AT上任意一点,求证:A′B+A′C≥AB+AC.分析如图1,若能把线段 AB 与 AC 合为三角形的一条边,利用三角形两 It is difficult to prove the inequalities and there are many methods. It is impossible to generalize, but there are many problems with the line segments. The key is to solve the problem of moving segments. As long as the line moves in place, the fortress will overcome. The following, we passed several One example, to understand the essence of this method. Example 1 A′ is known as the △ABC of the external angle bisector at any point on the AT, verify: A′B+A′C≥AB+AC. Analysis of Figure 1, if able Combine segments AB and AC into one side of a triangle, using two triangles