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!

Homework Help: Identities simplify expression

  1. Dec 12, 2009 #1
    I have been trying to do this problem for a long time, and still can not do it. I know the answer is sin2x, but I have no idea how to do it:

    write expression as sine, cosine, or tangent of an angle

    sin3xcosx - cos3xsinx

  2. jcsd
  3. Dec 12, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper

    Use the sine addition formula, sin(a-b)=sin(a)cos(b)-cos(a)sin(b). Line that up with your expression and figure out what a and b should be.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook