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Math Help - Look here, need help.

  1. #1
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    Look here, need help.

    I believe I am capable of doing the question. I just have no clue what it is asking me to do. Here's the question:

    "Determine the EXACT value of p(7pi/12), that is sin(7pi/12) and cos(7pi/12) by letting alpha = (pi/4) and beta = (pi/3)"

    .. Yup, no clue. Help is appreciated.
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  2. #2
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by MathNoobie View Post
    I believe I am capable of doing the question. I just have no clue what it is asking me to do. Here's the question:

    "Determine the EXACT value of p(7pi/12), that is sin(7pi/12) and cos(7pi/12) by letting alpha = (pi/4) and beta = (pi/3)"

    .. Yup, no clue. Help is appreciated.
    \frac{\pi}{4} + \frac{\pi}{3} = \frac{7 \pi }{12}

    So what are sin(\alpha + \beta) and cos(\alpha + \beta)?

    -Dan
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  3. #3
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by MathNoobie View Post
    I believe I am capable of doing the question. I just have no clue what it is asking me to do. Here's the question:

    "Determine the EXACT value of p(7pi/12), that is sin(7pi/12) and cos(7pi/12) by letting alpha = (pi/4) and beta = (pi/3)"

    .. Yup, no clue. Help is appreciated.
    does this help?

    \sin \bigg( \frac {7 \pi}{12} \bigg) = \sin \bigg( \frac {4 \pi}{12} + \frac {3 \pi}{12} \bigg) = \sin \bigg( \frac {\pi}3 + \frac {\pi}4 \bigg) = \sin ( \beta + \alpha )

    a similar manipulation should be done with cosine

    Now, you should know that:

    \sin ( \alpha + \beta ) = \sin \alpha \cos \beta + \sin \beta \cos \alpha

    and

    \cos ( \alpha + \beta ) = \cos \alpha \cos \beta - \sin \alpha \sin \beta
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