Which circles have a circumference of 24pi units?
choose all answers that are correct.
a.
a circle with a radius of 6 units
b.
a circle with a radius of 12 units
c.
a circle with a diameter of 12 units
d.
a circle with a diameter of 24 units

The answer is C. a circle with a diameter of 12 units. The circumference of the circle with the radius r is: C = 2 r π. We know that circumference is 24π units. So: C = 2rπ and C = 24π units. Therefore: 2rπ = 24π. Divide both sides by π: 2rπ / π = 24π / π. Thus: 2r = 24. r = 24/2. r = 12 units.