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Math Help - simplify and proof that answer is this

  1. #16
    MHF Contributor MarkFL's Avatar
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    Re: simplify and proof that answer is this

    What do you have so far for the first one?
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  2. #17
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    Re: simplify and proof that answer is this

    i dont know what to do with 1/2 sin (alpha) how to simplify it with
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  3. #18
    Forum Admin topsquark's Avatar
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    Re: simplify and proof that answer is this

    I previously posted:

    Quote Originally Posted by topsquark View Post
    sin(A - B) = sin(A)~cos(B) - sin(B)~cos(A)

    so we have:
    sin \left ( \frac{\pi}{3} - \alpha \right ) = sin \left ( \frac{\pi}{3} \right ) ~cos( \alpha ) - sin( \alpha) ~cos \left ( \frac{\pi}{3} \right )
    Fill in the sines and cosines of this line. Finish this line and you'll know what to do with the extra term.

    Basically what I'm asking you to do is the following:
    sin \left ( \frac{\pi}{3} \right )

    and
    cos \left ( \frac{\pi}{3} \right )

    -Dan
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  4. #19
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    Evander Mpumalanga South Africa
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    Re: simplify and proof that answer is this

    What is the answer to problem 1? Is it 0.8660Cosa?
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  5. #20
    Forum Admin topsquark's Avatar
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    Re: simplify and proof that answer is this

    You need to simplify
    sin \left ( \frac{\pi}{3} - \alpha \right )  - \frac{1}{2} sin( \alpha )

    I gave you a way to expand out the sin \left ( \frac{\pi}{3} - \alpha \right )

    When you do so you will see what to do with the sin(a) term.

    I think your biggest problem is that you are using a calculator. Put it away. If you work with exact answers you will easily see what to do.

    So again I ask you: What are
    sin \left ( \frac{\pi}{3} \right )

    and
    cos \left ( \frac{\pi}{3} \right )

    -Dan
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