How do you differentiate $cos 2x$ ?

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Answer 1 · 2017-01-03T01:13:00

We let $y = cosu$ and $u = 2x$ . Then $dy/(du) = -sinu$ and $(du)/dx= 2$ .

$dy/dx = dy/(du) xx (du)/dx$

$dy/dx = -sinu xx 2$

$dy/dx = -2sinu$

Since $u = 2x$ :

$dy/dx = -2sin2x$

Hopefully this helps!

How do you differentiate cos 2xcos 2x?