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(续前 )1 46 教学椭圆的标准方程时 ,要注意些什么 ?答 :(1 )把椭圆的位置特征与标准方程的形式统一起来。椭圆的位置由其中心的位置和焦点的位置确定。即 :如果椭圆的中心在原点 ,焦点在ｘ轴上 ,那么这个位置是标准位置 ,此时由于长轴也在ｘ轴上 ,半长轴的平方ａ2 是方程中含
(Continued) 1 46 What should we pay attention to when teaching the standard equations of ellipses? A: (1) Unite the positional features of the ellipse with the standard equations. The position of the ellipse is determined by the position of its center and the position of the focus. That is: if the center of the ellipse is at the origin and the focus is on the x-axis, then this position is the standard position. Since the long axis is also on the x-axis, the square of the semi-major axis is a2.