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在初三专题复习到动态几何问题时,学生都认为思路难找,分类标准难定,分数难得全.经过师生的共同研究、讨论,发现了动态几何题的一般解题思路:(1)充分认识图形的性质;(2)演示动态过程,发现变化规律;(3)确定分类标准;(4)找新旧图形元素之间的关系,针对各种情况进行计算.下面举例说明.一、平移例1(2008年荆州)如图1,等腰直角三角形纸片ABC中,AC=BC=4,∠ACB=90°,直角边AC在x轴上,B点在第二象限,A(1,0),AB交y轴于E,将纸片过E点折叠使BE与EA
In the third special subject to review the dynamic geometric problems, the students think the idea hard to find, difficult to set the classification criteria, a rare score.After the teachers and students to study, discuss and found the dynamic geometry of the general problem solving ideas: (1) Fully understand the nature of graphics; (2) demonstrate the dynamic process and find the law of change; (3) determine the classification criteria; (4) find the relationship between the old and the new graphic elements for a variety of situations. Example 1 (Jingzhou, 2008) In Fig. 1, the isosceles right triangle paper ABC has AC = BC = 4, ∠ACB = 90 °, right angle AC on the x axis, point B in the second quadrant, A , 0), AB cross the y-axis at E, the paper folded over E BE and EA