Final Answer
$-\sin\left(y\right)$
Got another answer? Verify it here!
Step-by-step Solution
Specify the solving method
1
Simplifying
$\frac{d}{dx}\left(\cos\left(y\right)\right)$
2
The derivative of the cosine of a function is equal to minus the sine of the function times the derivative of the function, in other words, if $f(x) = \cos(x)$, then $f'(x) = -\sin(x)\cdot D_x(x)$
$-\sin\left(y\right)$
Final Answer
$-\sin\left(y\right)$