Answer
$2$, $\frac{2\pi}{3}$, $-\frac{\pi}{6}$.
See graph.
Work Step by Step
1. Given $y=2cos(3x+\frac{\pi}{2})=2cos[3(x+\frac{\pi}{6})]$, we can find the amplitude $|A|=2$, period $p=\frac{2\pi}{3}$, and phase shift $-\frac{\pi}{6}$.
2. See graph.
