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Math Help - Finding solutions to this annoying equation ..

  1. #1
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    Red face Finding solutions to this annoying equation ..

    Find solutions for Sin(2x)-Sin(x)-Cos(x)+1=0

    I have been trying to come up with my own ways but I keep failing =\

    I tried squaring both sides after moving cos(x) to the other side ... I tried making 1 = Sin^2(x)+Cos^2(x) and solving it out .. But I just cant get it right !!!!

    Any help please ?

    Really appreciated
    Thanks
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  2. #2
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     \sin(2x) = 2\sin(x)\cos(x)
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  3. #3
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    I did try that =\
    This is all I got :

    http://img8.imageshack.us/img8/9008/22102009064.jpg
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  4. #4
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    Quote Originally Posted by ZaZu View Post
    Find solutions for Sin(2x)-Sin(x)-Cos(x)+1=0

    I have been trying to come up with my own ways but I keep failing =\

    I tried squaring both sides after moving cos(x) to the other side ... I tried making 1 = Sin^2(x)+Cos^2(x) and solving it out .. But I just cant get it right !!!!

    Any help please ?

    Really appreciated
    Thanks
    2 \sin x \cos x + 1 - (\sin x + \cos x) = 0

    Now substitute 1 = \cos^2 x + \sin^2 x and simplify:

    (\sin x + \cos x)^2 - (\sin x + \cos x) = 0.

    Factorise and then use the null factor law to get two simple trig equations. Solve them.
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