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!

Trigonometric Equations

  1. Feb 23, 2009 #1
    1. The problem statement, all variables and given/known data
    sin 2θ = sin θ Find the solutions in degrees.


    2. Relevant equations

    sin 2θ = 2sinθcosθ

    3. The attempt at a solution
    sin 2θ = sin θ
    2sinθcosθ = sin θ
    sinθ *cosθ/sin θ = 1

    That's as far as I can get, and I think that is wrong. How do I procede from 2sinθcosθ = sin θ?
     
  2. jcsd
  3. Feb 23, 2009 #2

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    One obvious possibility is [itex]sin(\theta)= 0[/itex]. What values of [itex]\theta[/itex] give that?
    IF [itex]sin(\theta)\ne 0[/itex], you can divide by it.

    So cancel the [itex]sin(\theta)[/itex]s, giving [itex]cos(\theta)= 1[/math]. What values of [itex]\theta[/itex] give that?

     
  4. Feb 23, 2009 #3
    Therefore the answer would be 0 degrees and 180 degrees? The book states that answers must greater or equal to one and less than 360.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Trigonometric Equations
  1. Trigonometric Equations (Replies: 42)

  2. Trigonometric equation (Replies: 4)

  3. Trigonometric equation (Replies: 5)

  4. Trigonometric Equation (Replies: 2)

Loading...