Answer:
18π inches (or approximately 56.549 inches)
Explanation:
The formula to find circumference is 2πr (or πd). Since we are given the radius (which is half of a circle), we will use 2πr, and the radius (or r) is equal to 9. So you just plug that into the circumference formula, and get:
2*π*9 = 18π
So, the circumference is 18π inches or approximately 56.549 inches (when rounded to the nearest thousandths).