Question

If the arc length of a sector in the unit circle is 4.2, what is the measure of the angle of the sector?

Answer 1

arc length = (Central Angle / 180) * PI * radius
4.2/ (PI * radius) = (Central Angle / 180)
It seems we also need the radius

Answer 2

If it is a unit circle, then radius = 1 then
arc length = radius * central angle
central angle in radians = arc length / radius
central angle in radians = 4.2 / 1
central angle in radians = 4.2
4.2 * (180/PI) = 4.2 * 57.2957795131=
240.6422739549 degrees