# How do you find the stationary points of the function y=cos(x)?

##### 1 Answer
Oct 30, 2014

$y = \cos x$

By taking the derivative,

$y ' = \sin x = 0 R i g h t a r r o w x = n \pi$, where $n$ is any integer

Since $y \left(n \pi\right) = \cos \left(n \pi\right) = {\left(- 1\right)}^{n}$,

its stationary points are $\left(n \pi , {\left(- 1\right)}^{n}\right)$ for every integer $n$.

I hope that this was helpful.