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Math Help - Some trigonometric functions questions

  1. #1
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    Thumbs up Some trigonometric functions questions

    Help needed on these also. Either solved or information to help me solve them myself would be vcery helpful. thanks a million.......

    1)Prove that:

    A) cosx/1-sinx - cosx/1+sinx = 2tanx

    B) sinx/sinx+cosx + cosx/sinx-cosx = 1/2sin^2x-1

    2) a) State the amplitude (A) the period(T) and the frequency(F) for
    the periodic function 120 sin(100pi t)V.

    b) Through how many degrees does a wheel rotate in 10ms if its
    angular velocity is 8 rad/s.

    c) Sketch one cycle of the given function showing the values of
    each variable where the curve crosses the axis.
    V=50sin(4.2*10^2t)
    Last edited by GAVREED2; May 24th 2010 at 07:14 PM.
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  2. #2
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    You may need to be a little more clearer with those proofs

    Quote Originally Posted by GAVREED2 View Post

    2) a) State the amplitude (A) the period(T) and the frequency(F) for
    the periodic function 120 sin(100pi t)V.
    For the function y=a\sin bx

    The amplitude is a, the period can be found by \frac{2\pi}{b}


    Have a read of this Trigonometric Functions
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  3. #3
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    Amended proofs

    Thanks so much for your input it was very helpful. i read the functions info and things are starting to become clearer. I also changed the format of the proofs if you could have a look that would be great....

    Quote Originally Posted by pickslides View Post
    You may need to be a little more clearer with those proofs



    For the function y=a\sin bx

    The amplitude is a, the period can be found by \frac{2\pi}{b}


    Have a read of this Trigonometric Functions
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  4. #4
    MHF Contributor harish21's Avatar
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    Quote Originally Posted by GAVREED2 View Post
    Help needed on these also. Either solved or information to help me solve them myself would be vcery helpful. thanks a million.......

    1)Prove that:

    A) cosx/1-sinx - cosx/1+sinx = 2tanx

    B) sinx/sinx+cosx + cosx/sinx-cosx = 1/2sin^2x-1

    2) a) State the amplitude (A) the period(T) and the frequency(F) for
    the periodic function 120 sin(100pi t)V.

    b) Through how many degrees does a wheel rotate in 10ms if its
    angular velocity is 8 rad/s.

    c) Sketch one cycle of the given function showing the values of
    each variable where the curve crosses the axis.
    V=50sin(4.2*10^2t)
    A) cosx/1-sinx - cosx/1+sinx = 2tanx

    \frac{cosx}{1-sinx} - \frac{cosx}{1+sinx}

    = \frac{cosx(1+sinx) - cosx(1-sinx)}{1-sin^{2}x}...simplifying this gives you 2tanx


    ----------------------------------------------------------
    B) sinx/sinx+cosx + cosx/sinx-cosx = 1/2sin^2x-1

    \frac{sinx}{sinx+cosx} + \frac{cosx}{sinx-cosx}

    \frac{sinx(sinx-cosx) + cosx(sinx+cosx)}{(sinx+cosx)(sinx-cosx)}

    \frac{sin^2x - sinx.cosx + sinx.cosx +cos^2x}{sin^2x-cos^2x}

    \frac{1}{sin^2x-(1-sin^2x)}

    \frac{1}{2sin^2x-1}
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  5. #5
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    Cheers!

    Can't thank you enough mate......

    Quote Originally Posted by harish21 View Post
    A) cosx/1-sinx - cosx/1+sinx = 2tanx

    \frac{cosx}{1-sinx} - \frac{cosx}{1+sinx}

    = \frac{cosx(1+sinx) - cosx(1-sinx)}{1-sin^{2}x}...simplifying this gives you 2tanx


    ----------------------------------------------------------
    B) sinx/sinx+cosx + cosx/sinx-cosx = 1/2sin^2x-1

    \frac{sinx}{sinx+cosx} + \frac{cosx}{sinx-cosx}

    \frac{sinx(sinx-cosx) + cosx(sinx+cosx)}{(sinx+cosx)(sinx-cosx)}

    \frac{sin^2x - sinx.cosx + sinx.cosx +cos^2x}{sin^2x-cos^2x}

    \frac{1}{sin^2x-(1-sin^2x)}

    \frac{1}{2sin^2x-1}
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