e=c/a
X^2/4-Y^2/3=1
a=2 b=根号3 c^2=4+3=7
c/a=根号7/2
顶点:(2,0) f1(-2,0)
设随圆:x^2/a^2+y^2/b^2=1
C=2
c^2=a^2-b^2=4
c/a=(根号7/2)/根号7=1/2
a=2c=4
b^2=4^2-2^2=12
椭圆方程:x^2/16+y^2/12=1
三角形ABF2的周长=AF1+AF2+BF1+BF2=2a+2a=4*4=16
三角形ABF2的面积=三角形F1BF2的面积+三角形F1AF2的面积
=|1/2(F1F2)*y1-1/2(F1F2)*y2|
=1/2(F1F2)*|y1-y2|
=1/2*(2c)*3
=3c
=6
圆C半径= 16/3.14/2=8/3.14
面积=3.14*(8^2/3.14^2)=64/3.14