定理三角形的内角平分线内分对边所得两线段与两邻边成比例.上述定理的证明方法较多,有十多种,同学们可尝试自己去证明.由于它是平面几何中重要而又基本的定理,故在解题中有着十分广泛地应用,下面以近几年的竞赛题为例来说明其应用. Theorem triangle internal bisector bisector of the two sides of the line is proportional to the two adjacent sides.The above theorems prove more, there are more than 10 kinds of students can try to prove themselves.Because it is important in plane geometry The basic theorem, so it has a very wide range of problems in the solution, the following contest in recent years as an example to illustrate its application.