Rewrite
2π/9  radians in degree measure

$${\frac{{\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{\pi}}}{{\mathtt{9}}}}$$ radians

 

$${\frac{{\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{\pi}}}{{\mathtt{9}}}}{\mathtt{\,\times\,}}\left({\frac{{\mathtt{180}}}{{\mathtt{\pi}}}}\right)$$

 

$${\frac{{\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{180}}}{{\mathtt{9}}}}$$

 

$${\frac{{\mathtt{360}}}{{\mathtt{9}}}}$$

 

$${\mathtt{40}}$$

 

$${\frac{{\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{\pi}}}{{\mathtt{9}}}}$$ radians is equal to $${\mathtt{40}}$$ degrees

From radian to degree, you multiply by 180º/π and reduce the fraction.

From degree to radian, you multiply by π/180º nad reduce fraction.

 

In this case, (2π/9)(180º/π)= 40º.