Question 924146
<pre>
You must memorize this:

(x-h)<sup>2</sup> + (y-k)<sup>2</sup> = r<sup>2</sup>

And that the center is (h,k) and the radius is r

Your equation is

x<sup>2</sup> + (y-3)<sup>2</sup> = 25

You want to rewrite it so that looks like this:

(x-h)<sup>2</sup> + (y-k)<sup>2</sup> = r<sup>2</sup>

To make x look like (x-h) write it as (x-0)
(y-3) already looks like (y-k)
To make 25 look like r<sup>2</sup>, write it as 5<sup>2</sup>

Then you have this equation:

(x-0)<sup>2</sup> + (y-3)<sup>2</sup> = 5<sup>2</sup>

And when you compare it to this equation which you memorize, 

(x-h)<sup>2</sup> + (y-k)<sup>2</sup> = r<sup>2</sup>

And you see that -0=-h or h=0, and -3=-k or k=3 and r<sup>2</sup>=5<sup>2</sup>
and so r=5.

So the center is (h,k) = (0,3) and radius = r = 5.  The graph is 

{{{drawing(400,400,-6,6,-3,9, graph(400,400,-6,6,-3,9,
3*sqrt(sin(7x))/sqrt(sin(7x))*sqrt(x)/sqrt(x)*sqrt(5-x)/sqrt(5-x)     ),
circle(0,3,5),locate(1,3,radius=5),
circle(0,3,0.15),circle(0,3,0.13),circle(0,3,0.11),circle(0,3,0.09),circle(0,3,0.07),circle(0,3,0.05),circle(0,3,0.03),circle(0,3,0.01) )}}}

Edwin</pre>