Answer:
18 units
Step-by-step explanation:
The centroid is located 1/3 the distance from the midpoint of a side to the opposite vertex. That means ...
CG = 2·DG = 6 + DG
Then
DG = 6 . . . . . . subtract DG from the above equation
Of course, ...
CD = CG +DG = 2·6 +6
CD = 18
