一、复习要点:(1)弄清垂线、斜线、四种命题、外心、内心、垂心、重心、外切、内切等基本概念。(2)要围绕公理和定理进行复习,如三角形中的公理、定理,各种特殊四边形的性质和定理,相似三角形的有关定理,在圆中,弧弦角的定理,切线割线的定理,与多边形的关系定理。(3)掌握计算公式,如三角形而积 S=1/2ah_a=1/2absinC,正、长方形面积,平行四边形面积 S=ah_a=absinα(α为 a·b夹角),菱形面积 S=aha=a~2sinα=1/2L_1L_2 First, the review points: (1) to identify the vertical, diagonal, four propositions, the outer heart, heart, vertical, center of gravity, externality, internal cutting and other basic concepts. (2) To review the axioms and theorems, such as the axioms in the triangle, the theorems, the properties and theorems of the special quadrilaterals, the related theorems of the similar triangles, the theorems of the arcs in the circles, the theorems of secant secant, Relationships with polygons. (3) Grasp the formula, such as triangular product S = 1 / 2ah_a = 1 / 2absinC, positive and rectangular area, parallelogram area S = ah_a = absinα (α is a · b angle), the diamond area S = aha = a ~ 2sinα = 1 / 2L_1L_2