Instead use WolframAlpha.com for math questions I would paste the answer but a cretinous fop has "disabled" that feature by javascript -- which is trivial to circumvent but I won't bother with the time.
Answer:
pi times d
Step-by-step explanation:the actuall formula is 2 pi r but since the radius times 2 is the diameer its pi times d hope this helps god bless
Answer:it’s the first one
Step-by-step explanation: