Question 331905
{{{arc_length = (n/180)*Pi*r}}}
where {{{n}}} is measured in degrees

given:

{{{arc_length=3Pi}}}
{{{r=6}}}

{{{n= (arc_length*180)/(Pi*r)}}}
{{{n= 3Pi *180/( Pi*6)}}}
{{{n= 3cross(Pi) *180/ (cross(Pi)*6)}}}
{{{n= 3 *180/ 6}}}
{{{n= (cross(3)*180)/(cross(6)*2)}}}
{{{n= 180/2}}}
{{{n= 90}}}