Question

what is the equation of this circle ?

Answer 1

hmm how long is the radius of it?

Answer 2

\(\bf (x-{\color{brown}{ h}})^2+(y-{\color{blue}{ k}})^2={\color{purple}{ r}}^2

\qquad center\ ({\color{brown}{ h}},{\color{blue}{ k}})\qquad
radius={\color{purple}{ r}}\)

you're given all 3, so just plug them in