【复习目标】 理解比与比例、线段的比与成比例线段、相似三角形与相似多边形等慨念;掌握比例的各条性质、平行线分线段成比例定理、三角形一边的平行线的性质和判定定理以及相似三角形的判定和性质定理,并能熟练地运用这些定理进行比例变形、计算及一般的证明。 【Objective】 To understand the ratio and proportion, the proportion and proportion of line segments, similar to the concept of similar polygons and polygons; grasp the proportion of the nature of the parallel lines subdivision proportional proportional theorem, the parallel nature of the triangle side and judgment Theorem and similar triangle judgment and property theorem, and can proficiently use these theorems for proportional deformation, calculation and general proof.