The general form of the equation of a circle is:
(x - h)2 + (y - k)2 = r2
Where, (h, k) is the centre of the circle.
r is the radius of the circle.
Substituting the centre and radius of the circle in he general form:
⇒ (x - 0)2 + (y - 0)2 = 42
⇒ x2 + y2 = 16
Ans; equation of a circle with . Centre at the origin and radius 4 is:
x2 + y2 = 16
