- #1

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## Main Question or Discussion Point

Explain to me:

Why the 2πf came in front?

I lost touch and sort of forgot.

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- B
- Thread starter lioric
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- #1

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Explain to me:

Why the 2πf came in front?

I lost touch and sort of forgot.

Last edited by a moderator:

- #2

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This is the ~~derivation~~ differentiation chain rule: [tex]\frac{df(g(x))}{dx}=\frac{df}{dg}\cdot\frac{dg}{dx}[/tex]

Edited by mentor...

Edited by mentor...

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- #3

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could you please show me how this works with my example

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- #5

jedishrfu

Mentor

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##d/dt ( cos (2 * \pi * f * t) ) = ##

## = - sin ( 2 * \pi * f * t ) * d/dt ( 2 * \pi * f * t ) ##

## = - sin ( 2 * \pi * f * t ) * ( 2 * \pi * f ) ##

## = - ( 2 * \pi * f * t ) * sin ( 2 * \pi * f * t ) ##

- #6

mathman

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General formula. Let f'(x)=g(x), then f'(ax)=ag(ax).

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