Answer
Amplitude $\frac{1}{2}$, period $\pi$. See graph.
Work Step by Step
1. Given $y=-\frac{1}{2}cos(2x)$, we can identify its amplitude as $|A|=|-\frac{1}{2}|=\frac{1}{2}$ and period as $p=\frac{2\pi}{2}=\pi$
2. See graph for a two period interval.
