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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.
     
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