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Homework Help: Secx=4, help explain

  1. Sep 13, 2009 #1
    1. The problem statement, all variables and given/known data

    I was supposed to use my calculator to get the answer of secx=4 for the range 0 to 2pi. I use the Ti-89.

    2. Relevant equations

    calculator format solve (secx=4,x)

    3. The attempt at a solution

    I get an answer, but it has a weird notation at the end of 2pi.

    2pi(weird notation)1 +/- arccos (1/4) In radians, obviously

    The notation looks like a lower case e, but instead, it breaks about halfway under the top loop. Sorry, for my vague info. I can't take a picture of it because i don't half no camera
  2. jcsd
  3. Sep 13, 2009 #2
    The TI-89 has the weird symbol to let you know their are more than 1 solution. Take f(x)=cos(x) for example. If you input it into the 89 for where f(x) = 0 you should right away know that f(x) will cross 0 in more than 1 place. The 89 will give you something like (pi/2)(weird symbol). But you know right away from the graph (if you know what it looks like) that it does not only cross at pi/2 but at every half wavelength starting at pi/2 (if your talking of only the positive side).
  4. Sep 13, 2009 #3
    Alright, thank you.
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