Given the function
![f(x)=(1)/(3)\cos (2(x+\pi))](https://img.qammunity.org/2023/formulas/mathematics/college/oozhbz46sc7tmkph64xfhe300gk6hzl5b3.png)
Which is equivalent to
![\Leftrightarrow f(x)=(1)/(3)\cos (2x+2\pi))](https://img.qammunity.org/2023/formulas/mathematics/college/a2t41st0mk40x6app4ng8jcwehwqbw378g.png)
In general, a trigonometric equation has the following structure
![g(x)=A\cos (B(x-C))+D](https://img.qammunity.org/2023/formulas/mathematics/college/hozx39i8u9z8kwsjuvo4rek5igqwobdbx8.png)
Where A is the amplitude.
Therefore, the amplitude of our function is 1/3.
As for the minimum and maximum of the function, remember that the range of the cosine function is [-1,1]; therefore,
![\begin{gathered} \text{minimum(f(x))}=(1)/(3)(-1)=-(1)/(3) \\ \text{maximum(f(x))}=(1)/(3)(1)=(1)/(3) \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/hobulzudguhmlwxtfx4dujt45s1987arn4.png)
Furthermore, the midline of the graph is a parallel line to the x-axis that crosses the midpoint between the maximum and the minimum; in our case,
![\begin{gathered} ((1)/(3)+(-(1)/(3)))/(2)=0 \\ \Rightarrow\text{midline is y=0} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/l05ai6x8l720b5i7uiqbjo68a8v1j6hhu2.png)
Finally, the graph of the function in the [0,2pi] interval is