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Trigonometry Question

  1. Sep 15, 2004 #1

    404

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    How do I do this? Thanks.
     
  2. jcsd
  3. Sep 15, 2004 #2

    mathwonk

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    recall the emanings, with a picture, of these functions sin, cos, tan, using a unit circle. you may be able to just see it.
     
  4. Sep 16, 2004 #3

    HallsofIvy

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    Do you know that sin2(θ)+ cos2(θ)= 1? Since you know sin(θ)= 1/3, you can use that to find cos(θ). Now, how is tan(θ) defined?
     
  5. Sep 16, 2004 #4
    Take the arc sin of 1/3 - this will give you the angle, but it will be the principle angle (first quadrant). But, since Cos theta <0, you know it can't be in the first quadrant or fourth quadrant, so it must be in either the second or third quadrant. But, since sin theta is >0, it must be in the second quadrant. You should be able to get the correct angle from this info, and therefore the correct cosine and then - as was hinted before - remember the definition of tangent theta.
     
  6. Sep 17, 2004 #5

    404

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    I got it now, Thanks guys :)
     
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