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1不正常现象日常教学中,经常出现一些“怪”现象,令我们教师费解.如教师认为很简单的题,学生却发生了高错误率;教师认为很好理解的问题,很多学生却想不通等等.最近,笔者在高三一轮复习中,碰到了两个不正常现象,印象非常深刻.现象之一:一些重要的数学公式、定理等,学生记得,但不知其成因.如向量数量积的坐标运算,由a=(x_1,y_1),b=(x_2,y_2),学生知道a·b=x_1x_2+y_1y_2,为什么呢?几乎无人知晓;余弦定理
1 irregular phenomenon often appear some “strange ” phenomenon, so that our teachers understand, such as the teacher that is very simple question, students have a high error rate; teachers think it is a good understanding of the problem, many students are Can not figure out, etc. Recently, the author in the high school review, met two abnormal phenomena, the impression is very profound. One of the phenomena: some important mathematical formulas, theorems, etc., students remember, but I do not know the cause. The coordinate operation of vector quantity product is made by a = (x_1, y_1), b = (x_2, y_2), and the student knows that a · b = x_1x_2 + y_1y_2. Why? Almost unknown; cosine theorem