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Math Help - What is the circumference of a circle with a radius of 4.2 inches?

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    What is the circumference of a circle with a radius of 4.2 inches?

    What is the circumference of a circle with a radius of 4.2 inches?

    A) 13.2 in.
    B) 6.6 in.
    C) 8.4 in.
    D) 55.4 in.
    E) 26.4 in.
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  2. #2
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    Quote Originally Posted by Leo34005 View Post
    What is the circumference of a circle with a radius of 4.2 inches?

    A) 13.2 in.
    B) 6.6 in.
    C) 8.4 in.
    D) 55.4 in.
    E) 26.4 in.
    Please show your attempt and state where you get stuck.

    NB: I would appreciate that no other replies be given until the OP has done what I asked.
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    C = 2πr

    Since the radius = 4.2 inches, r = 4.2. So we have:

    C = 2π(4.2)
    ==> C = 8.4π
    ==> C ≈ 26.39 in^2

    Therefore, the answer is E
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  4. #4
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    Quote Originally Posted by Leo34005 View Post
    C = 2πr

    Since the radius = 4.2 inches, r = 4.2. So we have:

    C = 2π(4.2)
    ==> C = 8.4π
    ==> C ≈ 26.39 in^2

    Therefore, the answer is E
    Correct (except the unit is inches, not square inches).
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