问题
填空题
已知椭圆
|
答案
∵椭圆
x2 |
a2 |
y2 |
b2 |
| ||
3 |
∴c=
6 |
3 |
设M(x0,y0),A(x1,y1),B(-x1,-y1),
k1=
y0-y1 |
x0-x1 |
y0-y2 |
x0-x2 |
把M和A分别代入椭圆
x2 |
a2 |
y2 |
b2 |
y02-y12 |
x02-x12 |
b2 |
a2 |
3k2 |
9k2 |
1 |
3 |
∴k1•k2=
y0-y1 |
x0-x1 |
y0+y1 |
x0+x1 |
y02-y12 |
x02-x12 |
b2 |
a2 |
3k2 |
9k2 |
1 |
3 |