角平分线具有两条性质:a.对称性;b.角平分线上的点到角两边的距离相等.对于有角平分线时的辅助线的作法,一般有两种.(1)从角平分线上一点向两边作垂线;(2)利用角平分线,构造对称图形(作法是在一侧的长边上截取短边).通常情况下,出现了直角或是垂直等条件时,一般考虑作垂线;其它情况下考虑构造对称图形.至于选取哪种方法,要结合题目图形 Angle bisector has two properties: a. Symmetry; b. The distance between two points on the angle bisector is equal to each other. There are two general ways for the auxiliary bisector when there is angle bisector: (1) (2) use the bisector of angle to construct the symmetrical pattern (practice is to take the short side on the long side of one side). Under normal circumstances, when the conditions of right angle or vertical appear, Generally considered for vertical; in other cases, consider the construction of symmetrical graphics. As for the choice of which method to combine the title graphics