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人教版教材《数学必修2》第三章习题3.3B组第4题:已知A(-3,-4),B(6,3)到直线l:ax+y+1=0的距离相等,求a的值.这是一道很具有典型性和代表性的题目,是我们学习直线的一个很好的素材.笔者发现,这正是以下试题的原型2004年全国卷2理科第8题:在坐标平面内,与点A(1,2)距离为1,且与点B(3,1)距离为2的直线共有()(A)1条(B)2条(C)3条(D)4条于是,在课堂教学中作了如下的变式教
People’s Education Edition teaching materials “math compulsory 2” The third chapter exercise 3.3B Group Question 4: Known A (-3, -4), B (6,3) to the straight line l: ax + y +1 = 0 distance Equal, seeking the value of a.This is a very typical and representative of the subject, is a very good material for learning a straight line.The author found that this is the prototype of the following questions 2004 Volume 2 National Science 8 : (A) 1 Article (B) 2 Article (C) 3 lines at a distance of 1 from point A (1,2) and a distance of 2 from point B (3,1) within the coordinate plane (D) Article 4 Then, the following variant teaching was made in the classroom teaching