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在初中平面几何教学中,学生遇到增添补助线的题目,往往不知从何入手,有的学生由于添不出补助线而感到几何难学。我是这样进行指导,培养学生增添乎几补助线的能力的。一、教给学生增添补助线的思维方法,要求学生按下述办法进行。 1.加强审题。由结论细看图形,对照条件,选择证题用的定义、定理、推论或已做过的有关习题。 2.将题中图形与所选方法的图形进行比较。如题中确已具有所选方法的图形,则无需增添补助线。否则缺哪一部分,就要依据基本作图法补足之。补充部分,正是要增添的补助线。例1.已知△ABC
In the junior middle school geometry teaching, students encounter the problem of adding subsidy line, often do not know where to start, and some students feel difficult to add geometry as a result of Tim line. I did this to train students in their ability to add support. First, teach students to increase the line of thinking method, require students to follow the following methods. 1. Strengthen the trial. From the conclusion look at the graphics, control conditions, the choice of the definition of the title, theorem, inference or have done the exercises. 2. Compare the figure in the question with the figure in the selected method. If the question does have a graphic of the method of choice, there is no need to add a grant line. Otherwise, the lack of which part, we must make up for the basic mapping method. Supplementary part, it is to increase the subsidy line. Example 1. Known △ ABC