Derivative of cos(x)

Step-by-step solution

1. 1Derivative of cos
   $$\frac{d}{dx}\left[\cos \left(x\right)\right]=-\sin \left(x\right)$$

   The derivative of $\cos (x)$ is $-\sin (x)$ — a standard rule.

2. ✓Final Answer
   $$\frac{d}{dx}\left[\cos \left(x\right)\right]=-\sin \left(x\right)$$

   The first derivative simplifies to $-\sin \left(x\right)$.