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

Sin(t) - cos(t) can be rewritten as?

  1. Feb 27, 2009 #1
    The problem:

    sin(t) - cos(t) can be rewritten as ? - The answer is sqrt(2)cos(3PI/4 - t).

    there is an equation Re^(xt)cos(bt - angle).
    R = sqrt(A^2+B^2)

    So i get the following answer:

    sqrt(2)(cos(t - 3PI/4)).


    Why does the correct answer have the 3PI/4 switched with the t??
     
  2. jcsd
  3. Feb 27, 2009 #2

    Nabeshin

    User Avatar
    Science Advisor

    If you remember the graph of cosine, the property should come to mind that:
    cos(-x)=cos(x), which is what's being used here.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook