Adartboard has a diameter of 18 inches. what are its radius and circumference?

Diameter of the dartboard as given in the question = 18 inches
Then
Radius of the dartboard will be = 18/2 inches
                                                  = 9 inches
We already know that
Circumference of a circle = 2πr
We also know that the value of π = 3.14159
Then
Circumference of the dartboard = 2 * 3.14159 * 9 inches
                                                    = 56.548 inches
                                                    = 56.55 inches
So the radius of the dartboard is 9 inches and the circumference of the dartboard is 56.55 inches. I hope the procedure is absolutely clear to you.

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