Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

What identity is this?

  1. Feb 8, 2010 #1
    While seeing a signals example problem, I encountered this:

    cos^2 (wt+θ) = [1+cos(2wt+2θ)]

    What identity is this?
  2. jcsd
  3. Feb 8, 2010 #2

    Doc Al

    User Avatar

    Staff: Mentor

    That doesn't seem right. Looks like they missed a factor of 2:

    cos(2x) = 2cos^2(x) - 1
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook