设A(x0,y0),且X0>0,Y0>0,则ABCD面积=2x0*2y0
渐近线方程为x±y/b=0,将A(x0,y0)代入方程得y0=bx0,ABCD面积=2x0*2y0=4bx0^2
又x0^2+y0^2=2且y0=bx0,x0^2=2/(1+b^2),
则ABCD面积=2x0*2y0=4bx0^2=8b/(1+b^2)=b
1+b^2=8,b^2=7,b=√7
x^2=y^2/(b^2)
x^2+y^2=2
y^2/(b^2)+y^2=2
y^2=2b^2/(b^2+1)
x^2=y^2/(b^2)
=2/(b^2+1)
S=|2x|*|2y|=4|xy|=8b/(b^2+1)=b
b^2+1=8
b^2=7
b=√7(b>0)