Chapter 5 - Trigonometric Functions - Section 5.4 Graphs of the Sine and Cosine Functions* - 5.4 Assess Your Understanding - Page 431: 13

$\text{Amplitude}= 4$ $\text{Period}=T= \pi$

Recall: For $y=A\cos{({\omega}x)}$, we have: $\text{Amplitude}=|A|$ and $\text{Period}=T=\frac{2\pi}{\omega}$ In $y=-4\cos (2x)$ we have $A=-4$ and $\omega=2$, so $\text{Amplitude} =|-4|=4$ $\text{Period}=T=\frac{2\pi}{\omega}=\frac{2\pi}{2}=\pi$