## Calculus 10th Edition

The derivative is $-\pi*sin(t)$
This derivative requires you to remember two things: 1) The derivative of cos(t) is -sin(t). 2) $\pi$ is a constant and so doesn't affect the differentiation whatsoever. Hence the derivative is $\pi *\frac{d}{dt}cost$ which is $-\pi*sin(t)$