The formula to covert the radian into degrees is given by,
[tex]\text{Radian}\times\frac{180}{\pi}=\text{Degrees}[/tex]
To convert π/9 radian into degrees,
[tex]\frac{\pi}{9}\times\frac{180}{\pi}=\frac{180}{9}=20\text{ degrees}[/tex]
Answer: Option 2) 20 degree
