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!

2 Trig Equations! Answer one or the other is fine!

  1. Oct 19, 2009 #1
    Tan(x)=3 tan(x/2) solve where 0<x<2pi?

    sin3xcosx+cos3xsinx=1, where 0<x<2pi?

    tried a long time...
  2. jcsd
  3. Oct 19, 2009 #2
    what methods have you tried? A graphical method often leads to insights - plot the 2 graphs and see where they intersect. Then look for the reasons why and hey presto! the answer.
  4. Oct 19, 2009 #3
    My old (1954) CRC Mathematics Tables book has exact trig relationships for tan x, tan 2x, and tan 3x. Also sin x, sin 2x, sin 3x, sin 4x and sin 5x. Also cosines. (page 344)
    Bob S
  5. Oct 19, 2009 #4
    Hello BuffaloSoulja
    The second looks very much like an addition theorem:
    find alpha and beta and make the solution.
    greetings Janm
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook