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Math Help - Exact value of sin

  1. #1
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    Exact value of sin

    Find the exact value of sin(−712)
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  2. #2
    MHF Contributor
    Joined
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    sin(-7pi/12)
    = -sin(7pi/12)
    = -sin(pi/4 +pi/3)
    = -[sin(pi/4)cos(pi/3) +cos(pi/4)sin(pi/3)]
    = -[(1/sqrt(2))(1/2) +(1/sqrt(2))(sqrt(3)/2)]
    = -[1 /2sqrt(2) +sqrt(3) /2sqrt(2)]
    = -(sqrt(2) /4)(1 +sqrt(3)) -----answer.

    or,
    = -(1/4)[sqrt(2) +sqrt(6)] ---------answer also
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