gull0
幼苗
共回答了15个问题采纳率:86.7% 举报
到两个顶点的距离差的绝对值等于椭圆c的焦距
这个等价于求到两定点距离差为定值的方程
就相当于求一个双曲线的方程
首先先算出x=0时 y=2√3 y=-2√3
所以双曲线焦点为(0,2√3)(0,-2√3)
椭圆的焦距一半为√(16-12)=2
所以椭圆焦距为4
由椭圆定义可得 2a=4···a=2 ········································(1)
c=2√3···············································(2)
所以 b=√(12-4)=2√2···················································(3)
又焦点在y轴上,所以可以得到方程为
y^2/4-x^2/8=1
嗯,应该没错,思路就是这样的,你自己检验一下,好久没做了,也不知道错了没
1年前
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