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: Trigonometric problem

  1. May 25, 2004 #1
    How to solve: sin x + sin 3x + sin 2x = 1 + cos 2x + cos x, give general solution in radians for x.
    How to get start?
    Anyone could help me, please?
  2. jcsd
  3. May 25, 2004 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    Dearly Missed

    You will need the following identities:
  4. May 26, 2004 #3
    I have solved the problem. I have used the identities:
    sin x + sin y = 2 sin (x+y)/2 cos(x-y)/2 and cos 2x = 2 cos^2 (x) - 1.
    With these two identities, it's easy to solve the problem.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook