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在新编高中课本第二册,二次曲线一章的教学中,我有如下的体会:教材先介绍椭圆定义,“动点到两定点的距离之和等于定值的点轨迹叫椭圆”.然后据此定义导出标准方程,后来安排一个例题:(即现行教材中的例4)点M(x,y)到定点F(c,0)的距离和它到定直线l:x=a~2/c的距离的比是常数c/a(a>c>0),
In the second volume of the new high school textbook, the first chapter of the quadratic curve teaching, I have the following experience: The first introduction of the elliptical definition of the teaching material, “the sum of the distance from the moving point to the two fixed points is equal to the fixed point trajectory called the ellipse.” Then we derive the standard equation based on this definition and then arrange an example: (Example 4 in the current textbook) The distance from the point M(x,y) to the fixed point F(c,0) and it to the fixed line l:x=a~ The ratio of the 2/c distance is the constant c/a (a>c>0).