Answer:
∠72°.
Step-by-step explanation:
If a circle has a circumference of 20 and an arc with a length of 4, we can simply set up a ratio to determine the angle of the arc in degrees:
[tex]\frac{4}{20} = \frac{x}{360}[/tex]
Cross multiply:
[tex]1440 = 20x\\[/tex]
Divide both sides by '20':
x = 72°.
Therefore, the measure of the central angle of the arc is ∠72°.