Question 798473
You want the radius to be 4 units, so as to be center offset that many units.  You already know the given center, so


{{{highlight((x-2)^2+(y-4)^2=4^2)}}}
Notice how the "r" and the "k" would compare in the standard form.


Showing the lower half of the relation as a function, slightly narrowed view field:
{{{graph(300,300,-1,9,-1,9,4-sqrt(16-(x-2)^2))}}}