What is the derivative of $f(x)=secxcosx$ ?

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Answer 1 · 2015-11-12T03:55:51

$f'(x)=0$ for all $x != pi/2+pik$ ( $k$ an integer.)

For all $x$ in the domain of $secx$ , we have

$f(x) = secx cosx = 1/cosx cosx = 1$ .

So $f'(x) = 0$

What is the derivative of f(x)=secxcosx f(x)=secxcosx?