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Parametric equations and finding tangents from circles

  1. Mar 4, 2010 #1
    1. The problem statement, all variables and given/known data
    A circle has the parametric equations:
    x=1+2cos[tex]\theta[/tex]
    y=3+2sin[tex]\theta[/tex]

    dy/dx= -1/tan[tex]\theta[/tex]

    Find the tangent equation at the point with parameter [tex]\theta[/tex]
    2. Relevant equations
    y-y1=m(x-x1)


    3. The attempt at a solution
    I've tried putting dy/dx in as the gradient and then x1 and y1 as the parametric equations but i seem to come up with some really long equation that im sure isnt right.

    Any help at all would be greatly appreciated. Many thanks.
     
  2. jcsd
  3. Mar 4, 2010 #2

    Mentallic

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    Homework Helper

    You mean you don't think this is right?:

    [tex]y-3-2sin\theta=-cot\theta(x-1-2cos\theta)[/tex]

    Because it is :tongue:
     
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