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Math Help - Absolute Extrema, Local Extrema

  1. #1
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    Absolute Extrema, Local Extrema

    1)Find the absolute extrema of f(x) = sin x - cos x on the interval [ 0,∏ ].

    Answer: abs. max at √2 or (sqrt.2) at 3∏/4.

    2) State the intervals on which f(x)= cos x - sin x is increasing on the interval [-∏ , ∏], and name all the local extrema.

    Answer:



    Could use some advice and help getting started thx.
    Last edited by Johnny Walker Black; November 23rd 2009 at 06:14 AM.
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  2. #2
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    I don't understand what you mean by "throwing trigonometric identities into the equation". What can you do on, say, f(x)= sin(x)- cos(x)? Have you found its derivative?
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  3. #3
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    Quote Originally Posted by HallsofIvy View Post
    I don't understand what you mean by "throwing trigonometric identities into the equation". What can you do on, say, f(x)= sin(x)- cos(x)? Have you found its derivative?
    dy/dx = cos(x)+sin(x)
    cos(x)+sin(x)=0
    here's where i'm stuck how should i go about solving for x?
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