Anonymous
Anonymous asked in Science & MathematicsMathematics · 1 month ago

help with this trig problem!?

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  • Philip
    Lv 6
    1 month ago

    cosx = 5/13, x in (0,pi/2). (sinx)^2=1-(5/13)^2=(169-25)/169=(12/13)^2.

    then sinx = (12/13) and,tanx = sinx/cosx = (12/5). 

    Now tan(2x) = 2tanx/[1 - tan^2(x)]. For tanx = (12/5) we have tan(2x) =

    2(12/5)/[1 - (12/5)^2] = -(24/5)/[(12/5)^2 -1] = -(24/5)(5^2)/[12^2-5^2] =

    -120/(144-25) = -(120/119). 

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  • ted s
    Lv 7
    1 month ago

    tan 2x = sin 2x / cos 2x = 2 sin x cos x / [ cos² x - sin²x ]....cos x = 5 / 13 & sin x = 12/13...you finish

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