Question

Find the radius of a circle in which the central angle, a, intercepts an arc of the given length s.

Answer 1

We know that the arc lenght formula (when the angle is given in degrees) is given by:

s = (alpha/ 180)*pi*r

this implies that r= s*180/(alpha*pi)

If you substitute the given information

alpha = 108 and s= 4 km

we get that r= 2.12 km