Huh? this is very confusing 12
Answer:
18 inches.
Step-by-step explanation:
We can connect two points of a circle in many ways, as you can see in the picture below.
The longest straight line that you can draw to connect two points is the diameter, that is, the straight line that passes through the center of the circle.
If the circle has 9 inches of radius the diameter will be 9+9 = 18 inches.