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Homework Help: Find the period of the following function

  1. Sep 19, 2006 #1
    I was asked to find the period of the following function:

    f(x)= mod(sinx)/cosx + mod(cosx)/sinx

    Since modulus is defined as sqrt(x*x),

    mod(sinx)/cosx= (sqrt(1-cosx*cosx))/ cosx
    = sqrt(1/cosx*cosx -1) //Taking cosx into the square root
    = sqrt(secx*secx-1)
    = sqrt(tanx)
    = mod(tanx)

    and similarly, mod(cosx)/sinx = mod(cotx)
    which is not possible because if either cosx or sinx are negative, then mod(cotx) or mod(tanx) will be negative.

    Could someone point our where Im went wrong?
  2. jcsd
  3. Sep 19, 2006 #2


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    Dearly Missed

    1. cos(x)=sign(cos(x))*|cos(x)|
    2. sec(x)*sec(x)-1 equals tan(x) SQUARED.
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