离心率e=c/a=二分之根号二b^2=a^2-c^2=a^2-a^2/2=a^2/2b=c=a*√2/2tan∠ABF=tan(∠ABO+∠OBF)=(tan∠ABO+tan∠OBF)/(1-tan∠ABO*tan∠OBF)=(a/b+c/b) / (1-a/b*c/b)=(√2+1)/(1-√2)=-(√2+1)^2=-3-2√2...