Multiplication with modulus of function

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Discussion Overview

The discussion revolves around the expression involving the cosine function and its modulus, specifically whether the equation |Cos(theta)|*Cos(theta) can be equated to Cos^(theta). Participants explore the implications of the modulus on the values of Cos(theta).

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether |Cos(theta)|*Cos(theta) equals Cos^(theta), suggesting that it implies only positive values of Cos(theta) are considered.
  • Another participant responds that |Cos(theta)| is always positive, but Cos(theta) itself can be negative, leading to a distinction in the evaluation of the expression.
  • A further clarification indicates that |a|*a equals a^2 if a is non-negative, but equals -a^2 if a is negative, which adds complexity to the original question.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the original question, as there are differing interpretations of the expression and its implications based on the sign of Cos(theta).

Contextual Notes

The discussion highlights the need for careful consideration of the conditions under which the modulus and cosine function are evaluated, particularly regarding the sign of Cos(theta).

Silva_physics
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Hi!
Could anybody, please, tell me:
whether |Cos(theta)|*Cos(theta) = Cos^(theta) , because it means that only positive values of Cos(theta) are taken.
Am I right?:shy:
 
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= Cos^2(theta)
 
Silva_physics said:
Hi!
Could anybody, please, tell me:
whether |Cos(theta)|*Cos(theta) = Cos^(theta) , because it means that only positive values of Cos(theta) are taken.
Am I right?:shy:
That's not a well phrased question. |Cos(theta)| is necessarily positive but the "Cos(theta)" outside the "modulus" is not so resticted.

In general |a|*a is equal to [itex]a^2[/itex] if a is non-negative, but equal to [itex]-a^2[/itex] if a is negative.
 
Thanks:wink:
 

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