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Homework Help: Terminal arm Point P

  1. Jul 21, 2011 #1
    1. The problem statement, all variables and given/known data

    The coordinates of a point P on a terminal arm of an <Θ (theta) in standard position are given, where 0<Θ<2pi. Determine the exact values of sinΘ, cos Θ and tan Θ

    2h) (-2,6)

    2. Relevant equations

    r= X +y

    3. The attempt at a solution

    So, first i found r by using r^2 = x^2 + y^2

    and got r = √ 38

    Since √ 38 cannot be factored to any lower form, i left that as the r.

    Going to sin, I did op/hypotenuse

    and got 6/√ 38 . However, this seems to be completely wrong as the answer is somehow 3/√ 10

    I just dont see how that possible, anyone?
  2. jcsd
  3. Jul 21, 2011 #2


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    Science Advisor
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    Gold Member

    You forgot to square the x coordinate when you calculated r.
  4. Jul 21, 2011 #3
    oops, thanks sir.
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