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Math Help - Trig Help Please

  1. #1
    Bar0n janvdl's Avatar
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    Trig Help Please

    This is something I've never really gotten the hang of...

    If tan 20 = t ; how could the following be expressed in terms of t?

    a) tan 70
    b) tan 40
    c) tan 200
    d) sec 20

    My answers:

    a)  \frac{1}{t}

    b)  ?

    c)  t

    d)  \sqrt{(t^2 + 1)}
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  2. #2
    MHF Contributor red_dog's Avatar
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    b) \tan 2x=\frac{2\tan x}{1-\tan ^2x}

    \tan 40=\frac{2\tan 20}{1-\tan ^220}=\frac{2t}{1-t^2}
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  3. #3
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    Hello, janvdl!

    It looks like you've got the hang of it . . .


    If \tan 20 = t, how could the following be expressed in terms of t?

    a)\;\tan 70\qquad b)\;\tan 40\qquad c)\;\tan 200\qquad d)\;\sec 20

    My answers:

    a)\; \frac{1}{t}\qquad b)\;? \qquad c)\;t \qquad d)\;\sqrt{t^2 + 1}

    For (b), use the Double-Angle Identity: . \tan2\theta \:=\:\frac{2\tan\theta}{1 - \tan^2\theta}

    And your answers are correct . . . nice work!

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