对于比较复杂的几何证明题或求解题 ,如果条件不能直接适用定理 ,则往往需要添加辅助线 ,创造条件来应用定理 .而构造适当的三角形 ,就是一种添加辅助线的重要方法 .下面就有关问题中常见的构造方法举例说明 .一、求不规则多边形的角度或比较线段的大小关系 ,常需构造三角形 .? For more complex geometric proofs or problem solving, if conditions cannot directly apply to the theorem, it is often necessary to add auxiliary lines and create conditions to apply the theorems. Constructing appropriate triangles is an important way to add auxiliary lines. An example of the common construction method in the problem is explained. First, to find the angle of an irregular polygon or to compare the size of a segment, it is often necessary to construct a triangle.