Answer:
(x-1)^2 + (y+4)^2 = 81
Step-by-step explanation:
The equation of a circle can be written as
(x-h)^2 + (y-k)^2 = r^2
where ( h,k) is the center and r is the radius
The center is ( 1,-4)
and the radius is d/2 = 18/2 = 9
(x-1)^2 + (y- -4)^2 = 9^2
(x-1)^2 + (y+4)^2 = 81
