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Trigonometry question

  1. Aug 29, 2007 #1
    My teacher told me that

    C sin(k x) + D cos(k x) = F sin(k x+gamma)

    if neither C nor D is 0 (gamma is a phase angle). How do you derive the expression on the right of the equal sign from that on the left?
    Last edited: Aug 29, 2007
  2. jcsd
  3. Aug 29, 2007 #2
    While normally one would say C and D assume certain values, I'll let you find what those values are. Expand the expression on the right and equate the terms on both sides.
  4. Aug 29, 2007 #3
    Actually, I just found out that my course book provides the answer to my question. :blushing: Sorry for bothering! But thanks anyway.

    So, note to self: always look in your books before posting questions here.
  5. Aug 29, 2007 #4
    The relevant trig identity is [tex]\sin (A+B) = \sin A \cos B + \sin B \cos A[/tex].
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