Circle equation

Hey there, this is my first post here, so hello to everyone.

I have (so far) one question. I have a circle equation like

x²+y²-6y+6=0

I know, that on a paper, I can convert it to the "normal" circle equation, from which I can read the middle point and radius of the circle. And now my question is, how to convert in in maple? I am using the 11th version.

I have tried solving this equation and (x-a)² + (y-b)² = r², but it doesn't return what I want (however it worked, when I had "all" parameters like x² +y² +2x -4y -4=0).

Thank you for any of you help, I am sure this is nothing complicated so I get my answer soon ;).