Answer:
C = πd
C = 2πr
Step-by-step explanation:
To find the circumference of a circle, you can use either formula C = πd, or formula C = 2πr regardless of whether you are given the circle's radius or diameter.
If you know the radius and you choose to use formula C = πd, then you must first multiply the radius by 2, or double the radius, to find the diameter before using the formula.
If you know the diameter and you choose to use formula C = 2πr, then you divide the diameter by 2, or take half of the diameter, to find the radius before using the formula.
