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Math Help - Double Check exact value?

  1. #1
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    Double Check exact value?

    Could someone double-check this for me please?

    Find the exact value by using a half-angle identity.
    tan(7pi/8)

    My Answer:
    tan(7pi/8) can be turned into tan(7pi/4 /2). So then we use the half angle formula associated with tan: tan A/2=sin A/(1 cosA)

    That gives us tan(7pi/4 /2)=(sin 7pi/4)/(1 cos 7pi/4)
    =-sqrt2/2/(1 sqrt2/2)
    =-sqrt2(2 sqrt2)
    =-sqrt2(2-sqrt2)/2
    =(2-2sqrt2)/2
    =1-sqrt2
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  2. #2
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    Re: Double Check exact value?

    Anyone?
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