人说几何很困难,难就难在辅助线.可辅助线如何添,把握定理和概念.还要刻苦加钻研,找出规律凭经验.图中有角平分线,可向两边作垂线.也可将图对折看,对称以后关系现.角平分线平行线,等腰三角形来添.角平分线加垂线,三线合一试试看. People say geometry is very difficult, difficult in the auxiliary line can be auxiliary line how to Tim, grasp the theorem and the concept, but also hard study, to find out the rule of thumb experience. Diagonal bisector of the figure can be set to both sides of the vertical line. Can also be folded on the map to see the relationship after the present symmetry. Angle bisector parallel lines, isosceles triangle to Tim. Angle bisector plus vertical, three-in-one try.