Final answer:
The circumference of a circle with a radius of 21 cm can be calculated using the formula C = 2πr, where π is approximately 3.14. The circumference is 132 cm.
Step-by-step explanation:
The circumference of a circle can be found using the formula C = 2πr, where π is a mathematical constant approximately equal to 3.14 and r is the radius of the circle. In this case, the radius is given as 21 cm, so the circumference can be calculated as follows:
C = 2(22/7)(21 cm) = 2(66 cm) = 132 cm
Therefore, the circumference of a circle with a radius of 21 cm, using π as 22/7, is 132 cm.