Answer:
A) 125.6 inches
Step-by-step explanation:
1. The radius: As you said, it is half the diameter, so it is 40/2, which is <em>20 inches</em>.
2. Plug in numbers into the equation: r = 20 inches, π = 3.14
<em>C = 2 * 3.14 * 20 inches</em> (of course, it was unnecessary to find the radius when we already have the diameter, but this was done to fit the given equation)
Multiply: C = 125.6 inches