## Intermediate Algebra for College Students (7th Edition)

Radius:$r=2$ and center: $(a,b)=(0,2)$
Use standard form of equation of circles; $(x-a)^2+(y-b)^2=r^2$ Here, $r$ defines radius and $(a,b)$ defines center. Then, $x^2+y^2-4y=0$ or, $x^2+(y^2-4y)=0$ or, $(x-0)^2+(y^2-4y+4)=4$ or, $(x-0)^2+(y-2)^2=2^2$ Thus, on comparing the above equation with the standard form, we have Radius:$r=2$ and center: $(a,b)=(0,2)$