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Math Help - Can I get some help with thismath question? (Circles/Arcs)

  1. #1
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    Can I get some help with thismath question? (Circles/Arcs)

    I just cant figure it out I really dont want to miss this questions ive been trying to figure it out for the past 30 minutes and I just cant seem to get it.

    I would appreciate it very very much if I could get help with this question.

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  2. #2
    Senior Member nikhil's Avatar
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    let angle be x radian then
    rx=2pi
    x=2pi/r
    x=2pi/12 (as r=12)
    as we know pi rad=180 degrees therfor
    x=(2pi/12)(180/pi) degrees
    x=180/6 degrees
    x=30 degrees
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  3. #3
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    I hope it is ok if I jump in here?

    If r is the radius? How would that tell the angle?

    I measured graphically and that is not a clear cut 30 degrees...

    //aha, the 2pi is the length of the arc... confusing measurement.. now I see it.
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    Last edited by ellensius; June 2nd 2010 at 05:47 AM.
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  4. #4
    Senior Member nikhil's Avatar
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    you measured the angle wow
    ok tell me are you sure that length of the arc is exatly 2pi.
    measuring from figure is a wrong method. in figure we may assign a value of 3 cm to a arc whose length is actually 3.02 cm. if we are using mathematical formulas no error will occur in result as result depends upon the magnitude of values and involved relation (as I used rx=2pi). measuring things using figure will not always give correct answer
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  5. #5
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    haha, I saw that later... too late, I had already posted it.

    I thought 2pi only was a notation to remind that 2pi = 360 degrees.
    I was really baffled, but realized it was so weird I must have made an error myself... I guess this was not the most graphically strong question.
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