| PF2 |
| sin∠PF1F2 |
| PF1 |
| sin∠PF2F1 |
则由已知得:
| a |
| PF2 |
| c |
| PF1 |
即:aPF1=cPF2
设点P(x0,y0)由焦点半径公式,
得:PF1=a+ex0,PF2=a-ex0
则a(a+ex0)=c(a-ex0)
解得:x0=
| a(c-a) |
| e(c+a) |
| a(e-1) |
| e(e+1) |
由椭圆的几何性质知:x0>-a则
| a(e-1) |
| e(e+1) |
整理得e2+2e-1>0,解得:e<-
| 2 |
| 2 |
故椭圆的离心率:e∈(
| 2 |
故选D.
| x2 |
| a2 |
| y2 |
| b2 |
| a |
| sin∠PF1F2 |
| c |
| sin∠PF2F1 |
| 2 |
| ||
| 2 |
| ||
| 2 |
| 2 |
| PF2 |
| sin∠PF1F2 |
| PF1 |
| sin∠PF2F1 |
| a |
| PF2 |
| c |
| PF1 |
| a(c-a) |
| e(c+a) |
| a(e-1) |
| e(e+1) |
| a(e-1) |
| e(e+1) |
| 2 |
| 2 |
| 2 |