Question 1083072
The radius is needed and the distance formula will find it.
sqrt{(4^2+7.5^2)=sqrt(72.25)=8.5.  Actually, don't need the square root since the equation of a circle deals with the square of the radius.
x^2+(y-9)^2=72.25
{{{graph(300,300,-10,30,-10,30,9+sqrt(-x^2+72.25),9-sqrt(-x^2+72.25))}}}