Chapter 6 - 6.4 - Graphs of Sine and Cosine Functions - 6.4 Exercises - Page 464: 11

$Amplitude=\frac{5}{3}$ $Period=24$

If $y=a~cos(bx)$ $Amplitude=|a|$ $Period=\frac{2\pi}{b}$ $y=-\frac{5}{3}~cos(\frac{\pi x}{12})$ $Amplitude=|-\frac{5}{3}|=\frac{5}{3}$ $Period=\frac{2\pi}{\frac{\pi}{12}}=2\pi\frac{12}{\pi}=\frac{24\pi}{\pi}=24$