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Math Help - Solving a trig equation.

  1. #1
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    Solving a trig equation.

    Find the maximum(minus) answer of this equation:

    (sinx-2)(cosx+ \frac{\sqrt{3}}{2} )=0

    Is it - 30^0?

    Thanks.
    Last edited by mr fantastic; May 30th 2011 at 01:51 PM. Reason: Re-titled.
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  2. #2
    MHF Contributor Also sprach Zarathustra's Avatar
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    sinx-2 is never zero.

    so you left with:

    cosx=-sqrt(3)/2)

    can you find the solutions for that?
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  3. #3
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    Quote Originally Posted by Ellla View Post
    Find the maximum(minus) answer of this equation:

    (sinx-2)(cosx+ \frac{\sqrt{3}}{2} )=0

    Is it - 30^0?

    Thanks.
    There is a minimum at -30 degrees, yes.
    However, there are also solutions to f(x)=0.

    Are you looking for the graph minimum or solutions to f(x)=0 ?
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  4. #4
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    Quote Originally Posted by Also sprach Zarathustra View Post
    sinx-2 is never zero.

    so you left with:

    cosx=-sqrt(3)/2)

    can you find the solutions for that?
    x = \frac{\pi}{6} +2 \pi k...and what should I do next?

    Archie Meade:

    Well, the answer is degrees and I am looking for maximum not min. Thank you.
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  5. #5
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    Quote Originally Posted by Ellla View Post

    Archie Meade:

    Well, the answer is degrees and I am looking for maximum not min. Thank you.
    You did mention a "negative maximum",
    so are you looking for a point on the graph furthest below the x-axis?
    Also, if you are looking for a maximum of any kind,
    solving f(x) = 0 doesn't find it.

    The most negative value is a minimum.
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  6. #6
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    Quote Originally Posted by Archie Meade View Post
    You did mention a "negative maximum",
    so are you looking for a point on the graph furthest below the x-axis?
    Also, if you are looking for a maximum of any kind,
    solving f(x) = 0 doesn't find it.

    The most negative value is a minimum.
    Yes, sorry for not explaining properly what I was looking for.

    so are you looking for a point on the graph furthest below the x-axis?
    Yes.
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  7. #7
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    Are you attempting a solution using differentiation or by other means ?
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  8. #8
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    Quote Originally Posted by Archie Meade View Post
    Are you attempting a solution using differentiation or by other means ?
    This, If I have any problems I will let you know
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