Answer: We have to sketch the angle and find the reference angle for the 20:
[tex]\frac{8\pi}{3}[/tex]
The reference angle is an angle between the terminal side of the angle and the x-axis.
[tex]\theta_R=180^{\circ}-\theta[/tex]
The provided angle is:
[tex]\begin{gathered} \theta=\frac{8\pi}{3}=480^{\circ} \\ \\ 480^{\circ}=480^{\circ}-360^{\circ}=120^{\circ} \\ \\ \theta=120^{\circ} \end{gathered}[/tex]
Sketch of the angle:
Therefore the reference angle is:
[tex]\begin{gathered} \theta_R=180^{\circ}-\theta \\ \\ \theta_R=180^{\circ}-120^{\circ} \\ \\ \theta_R=60^{\circ} \end{gathered}[/tex]
