已知F1,F2是椭圆x22+y2=1的左右焦点,过F1作倾斜角为45°的直线与椭圆相交于A,B两点.(1)求△F2AB的

2025-05-11 18:30:18
推荐回答(1个)
回答1:

(1)由

x2
2
+y2=1 可得 a=
2
,b=1=c,
∴△F2AB的周长=4a=4
2

(2)把 y=x+1 代入 x2+2y2=2 得3x2+4x=0,
解得x1=0  x2=?
4
3
,y1=1,y2=?
1
3

∴|AB|=
(x1?x2)2+(y1?y2)2
=
4
2
3

(3)点F2到直线AB的距离d=
|1?0+1|
2
=
2

S=
1
2
?|AB|?d
=
1
2
?
4
2
3
2
=
4
3