1. Not finding help here? Sign up for a free 30min 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!

Finding angle X when given an inequation and a weird equation

  1. Jul 22, 2009 #1
    1. The problem statement, all variables and given/known data

    sin (x) + sin (2x) + sin (3x) = 0
    http://www4b.wolframalpha.com/Calculate/MSP/MSP531196eg6ff0edb8i9400000gb08c7ag3hfbfeh?MSPStoreType=image/gif&s=8 [Broken]

    Sorry for not following the recommended layout, it's just that this question boggles me and I don't know any relevant formulas or where to start.

    I know the http://www28.wolframalpha.com/input/?i=sin+x+++sin+2x+++sin+3x+=+0,+pi/2+<+x+<+pi"but I don't know how to get to it.

    Thanks in advance to whoever tries to help
     
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Jul 22, 2009 #2

    rock.freak667

    User Avatar
    Homework Helper

    Do you know a formula for sinP+sinQ? (or the sum to product formula for sin?)
     
  4. Jul 22, 2009 #3

    Mentallic

    User Avatar
    Homework Helper

    Use the double-angle formula to expand the [tex]sin(2x)[/tex] and [tex]sin(3x)[/tex] - notice that [tex]sin(3x)=sin(2x+x)[/tex] , then collect like terms and factor as much as possible while using [tex]sin^2(x)+cos^2(x)=1[/tex] to aid you in the factoring process.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Finding angle X when given an inequation and a weird equation
  1. Finding f(x) given limit (Replies: 35)

Loading...