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正方形形不仅具有四边形、平行四边形、矩形、菱形的所有性质,而且具有轴对称性和中心对称性的美,还体现了角平分线、线段垂直平分线等性质,以正方形为基的考题历来是中考数学命题的热点和焦点之一.这些题的结构特点是:利用正方形的一些性质,结合其它知识点构成中考题,题目形式多样,精彩纷呈,很好地考查了图形类的主要知识点,以及学生分析问题和解决问题的能力.解题的切入点就是很好的利用正方形的性质,再综合其它知识通盘考虑去解答.一、利用正方形的角是直角图1例1(2013年长春)如图1,MN是⊙O的弦,正方形OABC的顶点B、C在MN上,且点B是CM的中点.若正方形OABC的边长为7,则MN的长为.
The square shape not only has all the properties of quadrilateral, parallelogram, rectangle, rhombus, but also has the beauty of axial symmetry and center symmetry, and also embodies the properties of angle bisector, vertical bisector of the line segment. The square-based test has always been The structural characteristics of these questions are: the use of some of the nature of the square, combined with other knowledge points constitute the test questions, the title of various forms, brilliant, a good examination of the main points of the graphics class, As well as students ability to analyze and solve problems.The starting point is to solve the problem is to make good use of the nature of the square, and then comprehensive consideration of other knowledge to answer.First, the use of square angle is a right angle Figure 1 Example 1 (2013 Changchun) As shown in Fig. 1, MN is the chord of ⊙O, vertices B and C of the square OABC are on MN, and point B is the midpoint of CM, if the side length of the square OABC is 7, the length of MN is.