# How do you find cos 8(pi) by referring to the graph of the sine or cosine function?

Oct 29, 2015

$\cos \left(8 \pi\right) = 1$

#### Explanation:

Since $8 \pi$ is a multiple of the period of cosine function, you can write that:

$\cos \left(8 \pi\right) = \cos \left(0\right)$.

Now if we look at the graph of cosine function we see., that $\cos \left(0\right) = 1$. So finally we can write, that:

$\cos \left(8 \pi\right) = \cos \left(0\right) = 1$