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    Really need help with a couple of trig questions, I hope someone can help me. Thank you so much in advance!!!

    the angles x and y are acute and x is greater than y. Given that cosxcosy=1/4 and sinxsiny=1/4, find the values of cos(x+y) and cos(x-y) and hence find the values of x and y
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    Well, first of all cos (x + y) = cos x.cos y - sin x.sin y and cos (x - y) = cos x.cos y + sin x.sin y.
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    So, cos(x+y)= 1/4 - 1/4 = 0 and cos(x-y)= 1/4 + 1/4 = 2/4 = 1/2, right?
    We now know that
    cos(x+y)=0 and
    cos(x-y)= 1/2.

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    (Original post by Leen!)
    So, cos(x+y)= 1/4 - 1/4 = 0 and cos(x-y)= 1/4 + 1/4 = 2/4 = 1/2, right?
    We now know that
    cos(x+y)=0 and
    cos(x-y)= 1/2.

    I got up to there but I'm not sure how to solve cos(x-y)=1/2 :/
    Thank you for your help
    -missing lessons is not a good idea lol
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    (Original post by Lavanyaa)
    I got up to there but I'm not sure how to solve cos(x-y)=1/2 :/
    Thank you for your help
    -missing lessons is not a good idea lol
    Well what values of A do you know that satisfy cos A = 1/2?
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    (Original post by davros)
    Well what values of A do you know that satisfy cos A = 1/2?
    60 & 300?
 
 
 
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