Answer:
[tex]g(x)=2\cos \frac{2x}{3}[/tex]Explanation:
A cosine function is generally given as;
[tex]\begin{gathered} y=a\cos (b) \\ \text{where Amplitude }=|a| \\ \text{ Period }=\frac{2\pi}{|b|} \end{gathered}[/tex]Given the below function;
[tex]f(x)=\cos x[/tex]If we compare both functions, we'll see that a = 1 and b = 1.
If we need another function with double the amplitude, then the value of a in that function will be (a = 2 x 1 = 2).
If we're to have another function g(x), with a period of 3 pi, let's go ahead and determine the value of b in the second function;
[tex]\begin{gathered} \frac{2\pi}{b}=3\pi \\ 3\pi\cdot b=2\pi \\ b=\frac{2\pi}{3\pi} \\ b=\frac{2}{3} \end{gathered}[/tex]Since we now have that for the second function g(x), a = 2 and b = 2/3, therefore g(x) can be written as below;
[tex]g(x)=2\cos \frac{2x}{3}[/tex]
