Answer
$|A|=3$, $p=\frac{2\pi}{2}=\pi $, $\phi=-\frac{\pi}{2}$.
Step 2. See graph.
Work Step by Step
Step 1. Given $y=3cos(2x+\pi)=3cos[2(x+\frac{\pi}{2})]$, we can find the amplitude $|A|=3$, period $p=\frac{2\pi}{2}=\pi $, and phase shift $\phi=-\frac{\pi}{2}$.
Step 2. See graph.
