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以二次函数为载体的平行四边形存在性问题,是近几年中考压轴题的热点.这类问题立足基础,突出能力和数学思想的考查,对学生分析问题和解决问题的能力要求较高.特别是一类找平行四边形中顶点坐标问题,使学生倍感困难.很多教师对此问题利用实物来讲解,先画出图形,再利用一个小棍作为一条边去寻找.这样做,一是比较费时,二是考虑不全面,三是讲过之后学生不知道如何表述.笔者从几何图形性质入手进行分析,总结出一些规律.下面以几道中考题为例,谈谈二次函数背景下,平行四边形顶点坐标的求法.例1(2009福建莆田)已知,如图1,抛
The existence of parallelograms with quadratic functions as the carrier is a hot topic in the mid-term test in recent years.It is based on the foundation, emphasizing ability and mathematical thinking, and requires students to analyze and solve problems. In particular, a class of parallelogram to find the coordinates of the vertices, so that students feel more difficult.Many teachers use this kind of matter to explain, first draw the graphics, and then use a stick as an edge to look for. Time-consuming, the second is to consider not comprehensive, the third is after the students do not know how to express the author start with the analysis of geometric properties, summed up some of the rules to several test questions below, for example, talk about the secondary function background, parallel Quadrilateral vertex coordinate method. Example 1 (2009 Fujian Putian) is known, as shown in Figure 1, throwing