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Homework Help: Trig identiy prob

  1. Jun 13, 2009 #1
    hey guys just had a test, i got a trig proof prob with cot 3u, just wondering how u break it up. thanks
  2. jcsd
  3. Jun 14, 2009 #2


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    Homework Helper

    Break it up into what?

    the most I can tell you is that cot(3u)=1/tan(3u)

    and one can use the triple angle formula for tan3u and get another equivalent expression.
  4. Jun 14, 2009 #3


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    I take it you know [itex]\cot u=\frac{\cos u}{\sin u}[/itex]. We could express this in a whole lot of ways. So you may want to give us the entire question or the expression you are working towards.
  5. Jun 14, 2009 #4


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    As rockl.freak667 and Cyosis said, there are many different ways to "break up" such a function? What, exactly, was the statement of the problem?

    I think I would be inclined to write it as cot(3u)= cot(u+ 2u) and use "sum" formulas. That's because I don't happen to remember offhand the "triple angle formula" rock.freak667 mentioned!
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