根据椭圆的定义得:PF1+PF2=10,
根据双曲线的定义得:PF1-PF2=2
| 15 |
∴PF1=5+
| 15 |
| 15 |
在三角形PF1F2中,又F1F2=8
由余弦定理得:
cos∠F1PF2=
| PF 1 2+PF 2 2 −F 1F 2 2 |
| 2PF 1PF 2 |
| 4 |
| 5 |
P与双曲线二焦点F1F2连线构成三角形面积为S=
| 1 |
| 2 |
| 1 |
| 2 |
| 15 |
| 15 |
| 3 |
| 5 |
故选D.
| y2 |
| 25 |
| x2 |
| 9 |
| y2 |
| 15 |
| 5 |
| 15 |
| 15 |
| 15 |
| PF 1 2+PF 2 2 −F 1F 2 2 |
| 2PF 1PF 2 |
| 4 |
| 5 |
| 1 |
| 2 |
| 1 |
| 2 |
| 15 |
| 15 |
| 3 |
| 5 |