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Math Help - ratios and trig ratios

  1. #1
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    ratios and trig ratios

    If  a:b:c=7:8:9 ,
    find \cos A:\cos B:\cos C
    where a,b,c are the sides opposite to angles A,B,C in triangle ABC.


    please help me...
    Last edited by earthboy; November 7th 2011 at 09:47 AM.
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  2. #2
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    Re: ratios and trig ratios

    Quote Originally Posted by earthboy View Post
    If  a:b:c=7:8:9 ,
    find \cos a:\cos b:\cos c



    please help me...
    1. I assume that the a in cos(a) denotes the angle opposite the side a. To avoid some confusion I'll use \alpha to denote this angle. Consequently \beta, \gamma denote the angles opposite the sides b or c.

    2. Use a triangle with the side lengthes
    a = 7, b = 8, c = 9

    3. Use the Cosine rule to determine the cosine values of the corresponding angles.

    I've got:

    \cos(\alpha) : \cos(\beta) : \cos(\gamma) = 14 : 11 : 6
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  3. #3
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    Re: ratios and trig ratios

    yes there's a little confusion with the question. i have edited it
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