The given equation of circle is $x^2 + y^2$ – 4x – 8y – 45 = 0 ∴ $(x^2 - 4x) + (y^2 - 8y)$ = 45 ⇒ [$x^2$ – 4x + $(2)^2$] + [$y^2$ – 8y + $(4)^2$] = 45 + $(2)^2 + (4)^2$ ⇒ $(x - 2)^2 + (y - 4)^2$ = 45 + 4 + 16 ⇒ $(x - 2)^2 + (y - 4)^2$ = 65 ⇒ $(x - 2)^2 + (y - 4)^2$ = $(\sqrt{65})^2$ Comparing it with $(x - h)^2 + (y - k)^2$ = $r^2$, we have h = 2, k = 4 and r = 65. Thus co-ordinates of the centre are (2, 4) and radius is 65.