(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Find the Derivative of:

(ln(cos4x)) / 12x^2

2. Relevant equations

y' ln(x) = 1/x

3. The attempt at a solution

I have determined the correct answer, but I am still confused as to how I came to the solution. Starting with the numerator, the derivative of cos is -sin. This would produce ln(-4sin(4x)) in the numerator. Now, to take the derivative of the natural log, I would do ln(x)= 1/x, correct? So 1/-4sin(4x)?

Why does the final numerator come out to -4tan(4x)? I know I am missing a basic rule or overlooking something... but why does it become tangent?

Thank you

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# Homework Help: Derivatives of trigonometric functions - Question

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