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Math Help - Solving for 0 ≤ x ≤ 360

  1. #1
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    Solving for 0 ≤ x ≤ 360

    Oh man I suck at these. Can anyone help out please?

    Solve the following equations for 0 ≤ x ≤ 360

    a)  sin2x + sinx = 0

    b) 3cos2x + 2 + cosx = 0

    A kind of method would be fantastic, Thanks guys!
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  2. #2
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    Hello

    Quote Originally Posted by Nick87 View Post
    Oh man I suck at these. Can anyone help out please?

    Solve the following equations for 0 ≤ x ≤ 360

    a)  sin2x + sinx = 0
    Remember that \sin 2x=2 \sin x \cos x

    2 \sin x \cos x+ \sin x=0

    Factor by \sin x :

    \sin x (2 \cos x+1)=0

    So either \sin x=0, either 2 \cos x+1=0



    b) 3cos2x + 2 + cosx = 0
    note that \cos 2x=2 \cos^2 x-1.

    Then substitute t=\cos x and solve for t

    A kind of method would be fantastic, Thanks guys!
    We have someone fantastic around here
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  3. #3
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    We sure do. Thanks Moo!
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