Multiplication with modulus of function

Silva_physics

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?

Silva_physics

= Cos^2(theta)

HallsofIvy

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.

Silva_physics

Thanks