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Math Help - sin and cosine function

  1. #1
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    sin and cosine function

    sin and cosine function-q2.png
    Please need help with this question!
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  2. #2
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    Re: sin and cosine function

    Use (a+b)^2 = a^2+2ab+b^2.
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    Re: sin and cosine function

    I tried doing this and i ended up with 2sin(a)cos(a)=0 where a=alpha, but i am not too sure where to go from there?
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    Re: sin and cosine function

    Calmo
    Study trigonometry a little bit. you have to know that 2sinacosa=sin(2a)
    therefore you have to solve the equation sin(2a)=0 which is very easy...
    Last edited by MINOANMAN; March 15th 2013 at 02:05 AM.
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    Re: sin and cosine function

    OK
    2 sin A cos A = 0 that is when sinA = 0 or cos A = 0
    sin A = 0 when A = 0 or pi and cos A = 0 when A = pi/2
    I am sure you can finish it now
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