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Thread: exact value

  1. April 27th 2009, 04:22 PM #1
    jumpman23
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    Exclamation exact value

    find the exact value of sine, cosine, and tangent of the angle..

    7pi/12
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  2. April 27th 2009, 04:40 PM #2
    Soroban
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    Hello, jumpman23!

    Recall the compound-angle identities:

    . . \begin{array}{ccc}\sin(A\pm B) &=&\sin A\cos B \pm \cos A\sin B \\ \\[-4mm] \cos(A \pm B) &=& \cos A\cos B \mp \sin A\sin B \\ \\[-4mm] \tan(A \pm B) &=& \dfrac{\tan A \pm \tan B}{1 \mp \tan A\tan B} \end{array}

    Find the exact value of sine, cosine, and tangent of: . \frac{7\pi}{12}
    Note that: . \frac{7\pi}{12} \;=\;\frac{3\pi}{12} + \frac{4\pi}{12} \;=\;\frac{\pi}{4} + \frac{\pi}{3}


    Can you finish it now?
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