x1^2+x2^2=1
(x1+x2)^2-2x1x2=1
a^2-2a-1=0
(a-1)^2=2
a=1±根号2
因为|a|=|x1x2|<1,所以-1
tanθ+1/tanθ
=x1/x2+x2/x1
=(x1^2+x2^2)/x1x2
=1/a
=1/(1-根号2)
=-1-根号2
x1^2+x2^2=1
(x1+x2)^2-2x1x2=1
a^2-2a-1=0
(a-1)^2=2
a=1±根号2
因为|a|=|x1x2|<1,所以-1
tanθ+1/tanθ
=x1/x2+x2/x1
=(x1^2+x2^2)/x1x2
=1/a
=1/(1-根号2)
=-1-根号2