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Thread: circumference of a circle

  1. #1
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    Talking circumference of a circle

    If the circumference of a circle is 4*pi/3, then what is half of its area?

    a 2*pi/9
    b.4*pi/9
    c.8*pi/9
    d.2*pi squared/9
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  2. #2
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    Quote Originally Posted by Schatzle06 View Post
    If the circumference of a circle is 4*pi/3, then what is half of its area?

    a 2*pi/9
    b.4*pi/9
    c.8*pi/9
    d.2*pi squared/9
    $\displaystyle 2\pi r=\frac{4\pi}{3}$
    Divide by $\displaystyle \pi$ to get,
    $\displaystyle 2 r=4/3$
    Divide by 2,
    $\displaystyle r=2/3$.
    Thus,
    $\displaystyle A=\pi (2/3)^2=(16/9)\pi$
    Half of that is,
    $\displaystyle (8/9)\pi$
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