Chapter 6.4, Problem 20AYU

To determine

To calculate: the value of the amplitude and the period.

Answer to Problem 20AYU

  $\begin{array}{l}Amplitude=\frac{9}{5}\\ Period=\frac{4}{3}\end{array}$

Explanation of Solution

Calculate the amplitude A and $W:y=A\sin wx$ .

  $\begin{array}{l}y=\frac{9}{5}\cos \left(-\frac{3\pi }{3}x\right);\\ A=\left|-\frac{9}{5}\right|=\frac{9}{5}\\ w=\frac{3\pi }{2}\end{array}$

To calculate period, this formula must be used $T=\frac{2\pi }{w}$

  $T=\frac{2\pi }{\frac{3\pi }{2}}=\frac{4}{3}$