Answer
(a) $1$, $\frac{20\pi}{3}$, $\frac{3}{20\pi}$.
(b) see graph.
Work Step by Step
(a) Given $y=-cos0.3t$, we can find the amplitude as $1$, period as $\frac{2\pi}{0.3}=\frac{20\pi}{3}$, and frequency of the motion as $\frac{3}{20\pi}$.
(b) see graph.