Question

a sound wave is modeled with the equation y = 1/4 cos 2pie/3(theta) find the period explain your method, find the amplitude explain your method

Answer 1

If
\[y=A \cos (Bx)\]
then the period T is
\[T=\frac{2 \pi}{B}\]
In your question B is given as
\[\frac{2 \pi}{3}\]
Therefore the period T is given by
\[T=\frac{2 \pi}{\frac{2 \pi}{3}}\]

Answer 2

For the amplitude:
If
\[y=A \cos (Bx)\]
then the amplitude is |A|
What is A in your question?

Answer 3

@carcar3 Do you follow the explanations?