我们证几何题时,往往从图形中不能直接找到已知和求证之间的关系,因而常常需要添置辅助线。通过辅助线,把过分集中的条件分散开来,或把过分分散的条件集中起来,沟通图形之间的联系,从而找出证题途径,添置辅助线因题而异,方法多样,这就要求我们不断探索规律,经常积累方法。 When we verify a geometric problem, we often cannot find the relationship between known and verified directly from the graph, so we often need to add an auxiliary line. Through the auxiliary line, the condition of over-concentration is dispersed, or the condition of over-dispersion is concentrated, and the connection between graphs is communicated, so as to find out the ways of the examination questions, and to increase the number of auxiliary lines, the methods are various, and this requires that We constantly explore the laws and often accumulate methods.