Question

圆C1：x²+y²+2mx+4y+m²-5=0,圆C2：x²+y²-2

Answer 1

C1:(x+m)^2+(y+2)^2=3^2

C2:(x-1)^2+(y-m)^2=2^2

⑴、两圆外切,则两圆心间距离=5,

(m+1)^2+(2+m)^2=25

m^2+2 m+1+4+4m+m^2=25

2m^2+6m-20=0

m^2+3m-10=0

m=2或m=-5

外公切线长=✓(5^2-1^2)=2✓6

⑵、两圆相交,两圆心距离大于1小于5,

m^2+3m-10