三角形内角平分线与等腰三角形有着密不可分的联系.在许多几何问题中,遇到等腰三角形就会想到顶角的平分线,遇到角平分线又会想到构造等腰三角形.请看下面两句常用的口诀:角分线,遇平行,必出等腰三角形.角分线,加垂直,等腰三角必出现.下面举例加以说明一、角平分线+平行线$等腰 The bisector of the triangle inner angle is inextricably linked with the isosceles triangle. In many geometric problems, the isosceles triangle is thought of as the bisector of the vertex, and the bisector of the angle is thought of as the isosceles triangle. See below Two commonly used formulas: angular subdivision, case parallel, must have isosceles triangle, angular subdivision, plus vertical, isosceles triangle must appear. Here is an example to illustrate: 1. The angle bisector + parallel line $ isosceles