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: Critical Points of a trig function

  1. Jul 4, 2011 #1
    Trig function:-sinx+(1/2)sin2x(2)

    The criticial points are (pi), (pi/3), and (5pi/3).

    Am I correct?
     
  2. jcsd
  3. Jul 4, 2011 #2
    Is that the first derivative there, or is it not differentiated?
    [tex]-sin(x)+2sin(2x)[/tex]
     
  4. Jul 4, 2011 #3
    Yes, the first derivative.
     
  5. Jul 4, 2011 #4
    Well,
    Given that [itex]sin(2x) = 2sin(x)cos(x)[/itex], you could say the following:
    [itex]4sin(x)cos(x)-sin(x)=0[/itex]
    [itex]sin(x)(4cos(x)-1)=0[/itex]
    Using the zero product property, what are the solutions to that?
     
  6. Jul 4, 2011 #5
    I just want to know if my critical points are correct or not.
     
  7. Jul 4, 2011 #6
    No, they are not
     
  8. Jul 4, 2011 #7
    Is pi/2 a point instead of pi?
     
  9. Jul 4, 2011 #8
    I'm sorry.

    The derivative is sin2x-sinx
     
  10. Jul 4, 2011 #9
    In that case you were right.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook