Question

已知圆x^2十y^2=4和圆x^2十y^2十4x一4y十4=0关于直线L对称，求直线L方程

Answer 1

x^2+y^2=4......(1)

x^2+y^2+4x-4y+4=0......(2)

(2)-(1):

L:x-y+2=0