#### Answer

center: $(0, 0)$;
radius = $\sqrt5$ units
Refer to the image below for the graph.

#### Work Step by Step

RECALL:
The circle $x^2+y^2=r^2$ has its center at $(0, 0)$ and a radius of $r$ units.
The given circle can be written as $x^2+y^2=(\sqrt5)^2$.
This equation is in the same form as the one in the recall part above so its center is at $(0, 0)$ and its radius is $\sqrt5$ units.
Plot the points that are:
$\sqrt5$ units above the center: $(0, $\sqrt5$)$
$\sqrt5$ units below the center: $(0, -$\sqrt5$)$
$\sqrt5$ units to the left of the center: $(-$\sqrt5$, 0)$
$\sqrt5$ units to the right of the center: $($\sqrt5$, 0)$
(note: $\sqrt5 \approx 2.236$)
Then, connect the points using a curve to form a circle.
(refer to the attached image in the answer part above)