1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    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!

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

Similar Threads - Identities simplify expression Date
Diff eq with constants.. Eulers identity.. Yesterday at 3:32 PM
Simplifying with trig identities May 15, 2015
Simplify the matrix product to the identity Nov 16, 2014
Simplify with Trigonometric Identities Sep 6, 2014
Simplifying Trig Identities Jun 1, 2014