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Calculus - Algebra question

  1. Feb 25, 2005 #1
    The Numerical Values of the circumference and area of a circle add up to 16.
    Determine the radius to 4 sf.

    Well so far me and my friend have been working on this and all of our results have been different to the final question, :<

    We first tried to manipulate with the formula pi x r^2 = a without any success, it would be appreciated if someone could clarify this question.

    Yes, maybe not a very hard question but it has confused us.
     
    Last edited: Feb 25, 2005
  2. jcsd
  3. Feb 25, 2005 #2

    Integral

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    You know that the:

    Area + Circumferance = 16

    Area = [itex] \pi r^2 [/itex]
    Circuference = [itex] \pi r [/itex]

    all you need do is solve the above relationship for r.
     
  4. Feb 25, 2005 #3
    Denote the area as x and the circumference as y
    x + y = 16
    x=Pi(y/2)^2

    Then substitute y in terms of x in the second equation and solve it.
     
  5. Feb 25, 2005 #4
    Probably a typo, but I'm fairly sure that Circuference = [itex] 2\pi r [/itex]
     
  6. Feb 25, 2005 #5
    hah

    we had actually already got it, but we messed up the quadractic formula calculation.

    Btw for thoose who are wondering the answer was 1.4683
     
  7. Feb 25, 2005 #6
    why is this a "calculus-algebra" question?
     
  8. Feb 25, 2005 #7
    In the New Zealand Curriculum.

    Caculus is comprised of

    Complex numbers/algebra
    Differentiation
    Intergration
    Conics

    So by New Zealand standards this is an Calculus - Algebra question
     
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