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Homework Help: Tangent sum or difference

  1. Mar 6, 2010 #1
    I am trying to find the exact value for tan(15). I figure my equation as 40 - 30 to give the 15.

    when deriving my equation is where I have the problem. can anyone help please.

    (1-√(3)/3)/(1 + 1 * √(3)/3)
  2. jcsd
  3. Mar 6, 2010 #2


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    Looks good so far. To rationalize the denominator, multiply the top and bottom by (1-√(3)/3).
  4. Mar 6, 2010 #3
    [tex]40-30 \neq 15[/tex]
    I think you mean [tex]45-30[/tex]
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