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Math Help - Trigonometry cosine and sine rule

  1. #1
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    Trigonometry cosine and sine rule

    Number 11 in the attached document.

    I don't know how to do it .. I can't figure out what i'm supposed to do. Help please
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  2. #2
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    Re: Trigonometry cosine and sine rule

    So you only want people who have Microsoft Word to respond?
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  3. #3
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    Re: Trigonometry cosine and sine rule

    Yes son.
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  4. #4
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    Re: Trigonometry cosine and sine rule

    Hi,
    A=45
    B=60
    => C=75
    You have to use for the both questions the sin-Formula:

    i) sinA/a =sinB/b => sin45/a=sin60/b => (sin45)^2/a^2=(sin60)/b^2
    you have to introduce the values for sin45 and sin60 and to transform the expression
    ii) The solution is analog
    to use: sin75= cos15; cos(2x)=2*cos(x))^2 -1 =>cos(x) =root((1+ cos2x)/2) => cos15=root((2+root(3))/2) = 1/2*root(2*(1+ root(3))^2)= (1+root(3))/root(2),
    => sin75= (1+root(3))/root(2)
    Last edited by StefanTM; October 24th 2012 at 08:37 AM.
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