SOLUTION
The general form of cosine curve is:
[tex]\begin{gathered} y=A\cos (Bx) \\ \text{Where:} \\ \text{A is the amplitude} \\ B\text{ is the frequency} \end{gathered}[/tex]
From the question, we were given (0,4) shows that the cosine curve has an amplitude of 4, so A=4
To get the frequency (B):
[tex]\begin{gathered} f=\frac{2\pi}{\text{period}} \\ \text{period}=4\pi \\ f=\frac{2\pi}{4\pi} \\ f=\frac{1}{2}=B \end{gathered}[/tex]
So, therefore, the equation of the cosine curve is:
[tex]y=4\cos (\frac{1}{2}x)[/tex]
