2 PUNTS

This circle is centered at the origin, and the length of its radius is 2. What is

the circle's equation?

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