Answer:
72 degrees
Step-by-step explanation:
A central angle equals the degree of the arc.
If the circumference is 20 and the arc is 4 than means the
arc is 4/20= 1/5 of the circumference.
A circles circumference is also always equal to 360 degrees.
So we need to find out what 1/5 of 360 is to find the degree of the arc.
So then 1/5*360= 72
so the Arc is equal to 72 degrees of the whole circle, which means the central angle is equal to 72 degrees as well.
