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Homework Help: Forming a series

  1. Apr 17, 2010 #1

    CR9

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    1. The problem statement, all variables and given/known data

    3/(2√3)=cos(3t+4.189)

    and therefore,

    0.866=cos(3t+4.189)

    I need to solve for t.

    3. The attempt at a solution

    I know that cos^(-1)θ has 2 values for every 2 pi, that is at 30 and 330 degrees.

    But there is no limit given, so its probably from 0 to infinite,thus the question wants me to form a new series whereby by substituting n=0,1,2,3 and etc, I will be able to find t.

    I dont know how to form this new formula/series as I was not thought this chap in calculus 2 (my lecturer was way behiind schedule, hence she skipped it)

    Hope you guys can help me.

    Thanks alot.

    Best regards,
     
  2. jcsd
  3. Apr 17, 2010 #2

    LCKurtz

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    Science Advisor
    Homework Helper
    Gold Member

    Instead of writing 30 and 330, think about 30 and -30 and angles coterminal with those. Using radians like you should in a problem like this you could express those angles as

    [tex] 3t + 4.189 = 2n\pi \pm \frac \pi 6,\ n = -\infty..\infty[/tex]

    and solve for t. Is that 4.189 what you were really given or just a decimal approximation to it?
     
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