How to plot the graph of f(x)=cos 8(pi)?

Jul 28, 2015

The line $y = 1$.
First of all, note that there is no dependence of the function on $x$. Thus it is a constant function. We need to find the value of the function.
We know that the period of $\cos$ is $2 \pi$. Thus we write:
$\cos \left(8 \pi\right) = \cos \left(0 + 4 . 2 \pi\right) = \cos \left(0\right) = 1$
Thus the graph of the function is $y = 1$, a line parallel to the x-axis having y-intercept of 1.