4)

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

Arc length is the angle/360 times circumference. The diameter of the unit circle is 2. So the circumference of the unit circle is 2pi, if you use 3.14 for pi, then the circumference is 6.28. So your equation is

x/360 times 6.28=4.2, divide by 6.28, then multiply by 360

x=240.76432

Your answer rounded to the nearest thousanth is 240.764