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Why are equations written in double angle form?

  1. May 10, 2017 #1
    1. The problem statement, all variables and given/known data
    I guess this is a general question. in the book, it was originally in a normal form, but it was then converted into a double angle form, which I would have to use double angle forumla to compute, so whats the point of simplifying in the first place?
    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. May 10, 2017 #2


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    Homework Helper
    Gold Member

    I guess it depends on what your unknown quantities are. The formulae in the gray box are much simpler, so there is less opportunity to make a mistake. That would be one advantage. Also, if it is something that you are memorizing, it is less to memorize, rather than all of those sin(theta)cos(theta) etc, for example.
  4. May 10, 2017 #3
    I guess you are right, its more compact, easier to remember.
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