Math

What is the exact circumference of a circle with a diameter of 21 inches?

Is it 110.25p inches??

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asked by Jen
  1. In google type:

    circumference of a circle


    When you see list of results go on wikipedia.


    C = circumference

    d = diameter


    C = d*pi

    C = 21*3.14159

    C = 65.97339 in

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    posted by Bosnian
  2. Circumference = 2πr or dπ with d as diameter

    so circumference = 21π

    (it asked for "exact" circumference , so the answer has to be left in terms of π )

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    posted by Reiny

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