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Math Help - proof of trig identity

  1. #1
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    proof of trig identity

    (sinA+sinB)/(cosA+cosB) + (cosA-cosB)/(sinA-sinB) = 0

    Prove the above trig identity

    THANKYOU !
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  2. #2
    MHF Contributor alexmahone's Avatar
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    \frac{sinA+sinB}{cosA+cosB} + \frac{cosA-cosB}{sinA-sinB}
    = \frac{sin ^2A-sin ^2B+cos^2A-cos^2B}{(cosA+cosB)(sinA-sinB)}

    ( sin^2\theta+cos ^2\theta=1)

    = \frac{1-1}{(cosA+cosB)(sinA-sinB)}
    = 0
    Last edited by alexmahone; June 2nd 2009 at 03:10 AM.
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