(1)
y = x²/4,x² = 4y = 2*2y = 2py,p = 2,焦点F(0,1),在y轴上,所以椭圆的长轴也在y轴上.
c = 1
y²/a² + x²/b² = 1
e² = 1/2 = c²/a²,a² = 2c² = 2
b² = a² - c² = 2 - 1 = 1
y²/2 + x² = 1
(2)凭感觉,如果存在,T应为特殊点.选L与x轴垂直及重合时可以发现,此时以AB为直径的圆均过右顶点C(1,0),AC² + BC² = AB²
令AB的斜率为k,其余见图.
(1)
y = x²/4,x² = 4y = 2*2y = 2py,p = 2,焦点F(0,1),在y轴上,所以椭圆的长轴也在y轴上.
c = 1
y²/a² + x²/b² = 1
e² = 1/2 = c²/a²,a² = 2c² = 2
b² = a² - c² = 2 - 1 = 1
y²/2 + x² = 1
(2)凭感觉,如果存在,T应为特殊点.选L与x轴垂直及重合时可以发现,此时以AB为直径的圆均过右顶点C(1,0),AC² + BC² = AB²
令AB的斜率为k,其余见图.