题目
题型:广东难度:来源:
x2 |
9 |
y2 |
16 |
答案
∵F1(-5,0)、F2(5,0),PF1⊥PF2,
∴
y-0 |
x+5 |
y-0 |
x-5 |
∴x2+y2=25 ①,
又
x2 |
9 |
y2 |
16 |
∴
25-y2 |
9 |
y2 |
16 |
∴y2=
162 |
25 |
∴|y|=
16 |
5 |
∴P到x轴的距离是
16 |
5 |
核心考点
举一反三
x2 |
a2 |
(I)求双曲线C的离心率e的取值范围:
(II)设直线l与y轴的交点为P,且
PA |
5 |
12 |
PB |
| ||
2 |
x2 |
n |
n+2 |
x2 |
9 |
y2 |
16 |
y-0 |
x+5 |
y-0 |
x-5 |
x2 |
9 |
y2 |
16 |
25-y2 |
9 |
y2 |
16 |
162 |
25 |
16 |
5 |
16 |
5 |
x2 |
a2 |
PA |
5 |
12 |
PB |
| ||
2 |
x2 |
n |
n+2 |