e=c/a=gen2/2 c^2/a^2=1/2
设P(x,y) OP^2=x^2+y^2=7/4
PF1PF2=(-c-x,-y)(c-x,-y)=-c^2+7/4=3/4
so c^2=1 a^2=2 b^2=a^2-c^2=1
so x^2/2+y^2=1
打了一问 手就好累啊!
e=c/a=gen2/2 c^2/a^2=1/2
设P(x,y) OP^2=x^2+y^2=7/4
PF1PF2=(-c-x,-y)(c-x,-y)=-c^2+7/4=3/4
so c^2=1 a^2=2 b^2=a^2-c^2=1
so x^2/2+y^2=1
打了一问 手就好累啊!