Center of circle = (-3, 6)
Diameter = 6
General equation of circle: x² + y² = r²
our answer will be in the form:
(x+a)² + (y+b)² = r²
Substitute center values and radius:
a = 3 (x was -3 but we don't trust it! It should be positive instead of negative)
b = -6 (same rules apply. Don't trust the value in the center. Its the opposite.)
r = 6/2 which is 3
answer: (x+3)² + (y-6)² = 3²