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Cos(x) question! How would you call 'x'?

  1. Sep 10, 2011 #1
    So I have this integration to solve but I needed help and I just couldn't make up a term to call that 'x' ><!! the term that is inside the parenthesis!! I know I've learned it somewhere but I just can't remember and it's making me nuts! >A<

    Also, what would you do in order to solve an equation that involves lets say sin(x)/cos(2x) [its just made up so I can explain myself a little better :D] and you need to combine both terms... but in order to combine them you gotta make a substitution for that 'x' term ><

    thanks in advance :D
     
  2. jcsd
  3. Sep 10, 2011 #2
    Integration by Substitution? Let x = [tex] \theta [/tex]? The symbol [tex] \theta [/tex] is pronounced theta? No idea what you are talking about.

    Just so you know, there is no simpler form to:

    [tex]
    \frac{sin(\theta)}{cos(2 \theta)}
    [/tex]

    IT DOES NOT EQUAL:
    [tex]
    tan(\frac{1}{2} \theta)
    [/tex]

    No idea if this helps, still have no clue what you are asking...
     
  4. Sep 10, 2011 #3
    im just wondering for the name of that theta since it wont always be the same thing on all equations... it changes depending on what u are asked for... like x, theta, pi and so on... just he generic name of that >< sorry if I wasn't clear enough
     
  5. Sep 10, 2011 #4
    A variable? There's no set word to describe whatever variable you insert inside of a trigonometric function. You just say that it is the parameter in terms of which the function is defined...?
     
  6. Sep 10, 2011 #5

    Hurkyl

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    This is a function application expression:
    [tex]A(B)[/tex]
    It is composed of two subexpressions:
    • The expression [itex]A[/itex], which should be of function type
    • The expression [itex]B[/itex], whose type should be contained in domain of [itex]A[/itex]
    In such expressions, [itex]B[/itex] is sometimes called the "argument", such as in the sentence "[itex]B[/itex] is the argument passed into the function [itex]A[/itex]".
     
  7. Sep 10, 2011 #6
    Speaking as a programmer, given cos(x), x is the argument or parameter to the function cos(). It can be a literal, such as 20, a variable, or an expression.

    Fred
     
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