Answer:
[tex]y = 2 \: cos \: (\frac{1}{3} x)[/tex]
option C is the right option.
Explanation:
General expression of a cosine function is:
y=A cos k X
where A is amplitude and 2 pi/k is its period.
In our case,
[tex] - y = 2 \: cos \: (\frac{1}{3} x) \:[/tex]
has :
[tex]amplitude = 2 \\ period = 2\pi \times 3 = 6\pi[/tex]
hence, the right answer is of option C
hope this helps...
Good luck on your assignment..
