It is de juro dimensionless, SI said so, and your government most likely made it official. https://en.wikipedia.org/wiki/Radian#Dimensional_analysis https://en

It is de juro dimensionless, SI said so, and your government most likely made it official. https://en.wikipedia.org/wiki/Radian#Dimensional_analysis https://en.wikipedia.org/wiki/Radian#Dimensional_analysis https://en.wikipedia.org/wiki/Radian#As_a_SI_unit https://en.wikipedia.org/wiki/Radian#As_a_SI_unit I am not sure that the current definitions are consistent or useful, but I myself don't know better.