We will be finding the derivative of $-\sin x$. We first rewrite this expression as:
\[\begin{align*} -\sin x = -1 \cdot \sin x. \end{align*}\]
We can remove the $-1$ from the expression because it is a constant. Then, we recall that:
\[\begin{align*} \dfrac{d}{dx}(\sin x) = \cos x. \end{align*}\]
To learn about how we can prove this, check out this article: (insert derivative of sin x article). Finally, we add the $-1$ back into the equation to get our answer:
\[\begin{align*} -1 \cdot \dfrac{d}{dx}(\sin x) = \boxed{-\cos x}. \end{align*}\]
Remember you can ignore the constant, differentiate and then add the constant back. $-$ in front of the expression means $-1$.
