# What is the derivative of picosx?

Dec 14, 2015

$- \pi \sin x$

#### Explanation:

Remember that $\pi$ is just a constant. Don't let it cloud your thoughts when trying to differentiate.

The only other thing to know for this problem is that $\frac{d}{\mathrm{dx}} \left[\cos x\right] = - \sin x$.

Thus, the constant $\pi$ is kept at the front multiplied to the new derivative, so:

$\frac{d}{\mathrm{dx}} \left[\pi \cos x\right] = \pi \frac{d}{\mathrm{dx}} \left[\cos x\right] = \pi \times - \sin x = - \pi \sin x$