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Math Help - Please Help!

  1. #1
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    Please Help!

    I'm trying to figure out this mathbits homework. I don't think I'm getting this particular answer because the URL won't work.

    Find the exact value of sinetheta when costheta = 3/5 and the terminal side of theta is in quadrant four


    Thanks so much
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  2. #2
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    Quote Originally Posted by jlldbr216 View Post
    I'm trying to figure out this mathbits homework. I don't think I'm getting this particular answer because the URL won't work.

    Find the exact value of sinetheta when costheta = 3/5 and the terminal side of theta is in quadrant four


    Thanks so much
    All you need to do is draw a right triangle and solve it. Remember that cos(\theta)=\frac{adjacent}{hypotenuse}. The hypotenuse is 5, the adjacent side is 3, and so the pythagorean theorem gives x^2=25-9=16. So the remaining side is x=4. So sine should be \pm\frac{4}{5}. If the terminal side is in quadrant four, then what is the sign \pm of sine?

    sin(\theta)=-\frac{4}{5}
    Last edited by mr fantastic; January 6th 2010 at 08:20 PM.
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