The equation of the circle is, x2+y2−8x−2y+8=0 (x2+y2−8x−2y+8)+λ(x−2)=0 x2+y2+(λ−8)x−2y+(8−2λ)=0 For minimum radius, it is necessary that center of circle lies onthe line x−2=0, −(
λ−8
2
)−2=0 λ−8=−4 λ=4 So, the equation of the required circle is, x2+y2−4x−2y=0