1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Integral of cos^2 x

  1. Mar 22, 2013 #1
    1. The problem statement, all variables and given/known data

    I need to find ∫cos^2 x using cos x cos y = 1/2(cos(x+y)+cos(x-y)). Note that it is not cos to the power of 2x. It is cos to the power of 2 multiplied by x.


    2. Relevant equations

    cos x cos y = 1/2(cos(x+y)+cos(x-y))


    3. The attempt at a solution

    I've searched my textbook and online everywhere, but my teacher hasn't given me any guidance. All I can think of is somehow converting cos x cos y = 1/2(cos(x+y)+cos(x-y)) to cos2x so I can then use a general formula/rule. Any help is highly appreciated.
     
    Last edited by a moderator: Mar 22, 2013
  2. jcsd
  3. Mar 22, 2013 #2

    eumyang

    User Avatar
    Homework Helper

    Minor nitpick, but one does not say "multiplied" here. You read it as "cosine squared of x."

    If you are saying that
    [itex]\cos x \cos y = ... = \cos 2x[/itex],
    after you plug in x for y, that's not right. It should be
    [itex]\cos x \cos y = ... = \frac{1 + \cos 2x}{2}[/itex].
     
  4. Mar 22, 2013 #3
    By, after you plug in x for y, do you mean to say that you change cosxcosy to cosxcosx in order to satisfy cosine squared of x?
     
  5. Mar 22, 2013 #4

    eumyang

    User Avatar
    Homework Helper

    Yes.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Integral of cos^2 x
  1. Integral (cos x)^2? (Replies: 2)

  2. Integral of Cos^2(x) (Replies: 1)

  3. Cos^2(x) Integral (Replies: 5)

  4. Integral of cos(x^2) (Replies: 6)

Loading...