有实根则x是实数
x²-(tanθ+i)x-(2+i)=0
(x²-xtanθ-2)-(x+1)i=0
所以x²-xtanθ-2=0,x+1=0
x=-1
则1+tanθ-2=0
tanθ=1
θ=kπ+π/4
实数根是x=-1