In this case, we'll have to carry out several steps to find the solution.
Step 01:
Data
Center ( -8 , 7)
Diameter = 6
Step 02:
Circle equation
(x - xo) ² + (y - yo) ² = r ²
xo = - 8
yo = 7
r = d / 2 = 6 / 2 = 3
(x - (-8))² + (y - 7) ² = 3 ²
(x + 8) ² + (y -7)² = 9
The answer is:
(x + 8) ² + (y -7)² = 9
