Question 967391
Radius 100 means circumference is {{{2*pi*100=200pi}}}.  The given arc length is a fraction of the {{{200pi}}}, and therefore that fraction of the {{{2pi}}} radians.


Radian measure of the arc
{{{(250/(200pi))2pi=250/100=25/10=highlight(5/2)}}}, in radians.


Next use the fact,  {{{2pi}}} radians is 360 degrees.