I need to find the derivative of a function for a given value of the argument Can smb help?

Question

F(x) = ln cos x; F'(-pi/3)

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Answer 1 · 2018-06-11T23:28:07

#F'(-pi/3) = sqrt3#

Using the chain rule:

#(dF)/dx = 1/cosx d/dx cosx = -sinx/cosx = -tanx#

So:

#(dF)/dx|_(x=-pi/3) = -tan(-pi/3) = sqrt3#