Answer:
[tex]y = 5cos(\frac{2\pi }{6} x)[/tex]
Explanation:
You can put that equation into a program like desmos on your browser and take a screenshot or use windows snippet tool.
Equation of a Wave: y = Acos(((2*pi)/B)x)
or
[tex]y = Acos(\frac{2\pi }{B} x)[/tex]
A = Amplitude
B= Wavelength