关于三角形中位线有两个很重要的结论：其一是三角形的中位线平行于第三边；其二是三角形的中位线等于第三边的一半．利用这两个结论可以解决很多几何问题．下面举一些常见的例题，供同学们学习时参考．一、证明两直线平行例1已知：如国1，△ABC中，BE、CF分别为ABC和ACB的外角 There are two very important conclusions about the median line in the triangle: one is that the median line of the triangle is parallel to the third side; the other is the median line of the triangle is equal to half of the third side. Using these two conclusions can solve a lot of geometric problems. Here are some common examples for reference when students learn. I. Prove that two straight lines are parallel Example 1 is known: If country 1, △ABC, BE, CF are external angles of ABC and ACB, respectively