Given that polar form of the circle is r2−4r(cos‌θ+sin‌θ)−4=0 . . . (i0 Put ‌‌x=r‌cos‌θ and y=rsin‌θ ∴‌‌r2=x2+y2 From Eqs. (i) ‌r2−4(r‌cos‌θ+rsin‌θ)−4=0 ‌⇒‌‌x2+y2−4(x+y)−4=0 ‌⇒‌‌x2+y2−4x−4y−4=0 ∴ Centre of circle (2,2).
