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Homework Help: Conceptual trigonometry

  1. Nov 30, 2007 #1

    I'm really curious to know the rules of combining trig functions, say if:
    y = sin(x) + cos(2x)
    _How would I determine the period of the sinusoid (if it IS one)

    Is there a mthod of predicting if two sinusoids will compose another sinusoid, if there is I'm missing it. My text book says that 2*pi is always a good solution to check for, but what does that mean? How do I check?
    In the end, I really need a better means of learning Trig, my text makes too many conjectures w/o backing any of them up.

    Any hyelp woudl be appreciated!:confused:
  2. jcsd
  3. Nov 30, 2007 #2


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    Homework Helper

    Well you can use the factor formula of

    [tex]SinP+sinQ=2sin(\frac{P+Q}{2})cos(\frac{P-Q}{2})[/tex] and use the fact that sinx=cos(pi/2 -x)
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