Answer
See graph and explanations.
Work Step by Step
1. Rewrite the function as $y=\frac{1}{2}cos(\frac{\pi}{4} x)-2$, we have amplitude $\frac{1}{2}$, period $p=\frac{2\pi}{\frac{\pi}{4}}=8$.
2. Graph $y=cos(x)$ (blue), stretch horizontally by a factor of $\frac{4}{\pi}$, shrink vertically by a factor of 2, then shift the curve 2 units down to get $y=\frac{1}{2}cos(\frac{\pi}{4} x)-2$ (red).
