Answer:
x^2 + y^2 = 4
Step-by-step explanation:
The center-radius form (formally called the standard form) of a circle is
(x-h)^2+(y-k)^2=r^2 where (h,k) is the center and r is the radius.
So if we replace (h,k) with (0,0) since the center is the origin and r with 2 since the radius is 2 we get:
(x-0)^2+(y-0)^2=2^2
Let's simplify:
x^2 + y^2 = 4
