Respuesta :

Answer:

66 cm (Option B)

Step-by-step explanation:

The formula for the circumference of a circle is C = 2πr, so plug the values into the formula.  The radius, (r) of a circle is one half of the diameter, so split 21 is half to get a radius of 10.5.  Use 3.14 for π.  

C = 2πr

C = 2(3.14)(10.5)

C = 6.28 × 10.5

C = 65.94

Rounded to the nearest unit, you get a answer of 66 cm.  

Hope this helps!  :)