Answer:
x² + (y-3)² = 9, or x² + y² - 6y = 0
Step-by-step explanation:
The equation of a circle is
(x-h)² + (y-k)² = r², where (h, k) is the center of the circle and r is the radius.
In this circle, the center is at (0, 3) and the radius is 3:
(x-0)² + (y-3)² = 3²
x² + (y-3)(y-3) = 9
x² + y² - 3y - 3y + 9 = 9
x² + y² - 6y + 9 = 9
x² + y² - 6y + 9 - 9 = 9 - 9
x² + y² - 6y = 0
