添作辅助线是解几何题的重要手段,主要有两方面的作用: 1.将分散的图形联系起来,起“桥梁”作用.适当的辅助线如“一桥飞架南北”,使“天堑变通途”。例如,证明平行四边形的性质定理时,我们添作对角线(如图1中的AC),在遥遥相对的对边和对角间架起桥来,将它们分别置于 Adding an auxiliary line is an important means of solving geometric problems. It mainly has two functions: 1. Linking scattered graphs and acting as a “bridge.” Appropriate auxiliary lines, such as “a bridge fly north and south,” make Tianhe Change the road." For example, when we prove the property theorem of a parallelogram, we add a diagonal line (AC in Figure 1) to bridge between distant opposite sides and diagonal corners and place them separately.