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Math Help - trigonometry

  1. #1
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    trigonometry

    If , then the expression [√2+√2(1+cos4θ)]is simplified to _________ .
    1) 2cosθ
    2) 2sinθ
    3) -2cosθ
    4) -2sinθ
    (its a single choice question)
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  2. #2
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    Quote Originally Posted by gkpandey View Post
    If , then the expression [√2+√2(1+cos4θ)]is simplified to _________ .
    1) 2cosθ
    2) 2sinθ
    3) -2cosθ
    4) -2sinθ
    (its a single choice question)

    [√2+√2(1+cos4θ)]
    [√2+√2 . 2cos^2 2θ] [1+cos4θ=2cos^2 2θ , half the angle formula]
    √2{1+2cos^2 2θ]
    v2 {1+2(2cos^2 θ-1)
    v2{2cos^2 θ -1}
    Last edited by matsci0000; September 4th 2009 at 08:01 AM.
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  3. #3
    Member
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    Quote Originally Posted by gkpandey View Post
    If , then the expression [√2+√2(1+cos4θ)]is simplified to _________ .
    1) 2cosθ
    2) 2sinθ
    3) -2cosθ
    4) -2sinθ
    (its a single choice question)
    i think your question is

    √[2+√{2*(1+cos 4θ)}] = ?

    use identity
    1+cos2θ = 2 cos^2 θ
    and cos4θ =cos2(2θ )

    solve the sum to get answer
    1) 2cosθ
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