The circumference of a circle is calculated using the following equation:
Where d is equal to the diameter (the length of a straight line from one side of the circle to the other side).
We know that the diameter of the circle given (also known as AB) is equal to 20 cm.
We can then plug this into the equation and solve for the circumference:
Since the question asks for the answer to be in terms of
, this is as far as we need to go. So the circumference of the circle is: 
or D.
Where d is equal to the diameter (the length of a straight line from one side of the circle to the other side).
We know that the diameter of the circle given (also known as AB) is equal to 20 cm.
We can then plug this into the equation and solve for the circumference:
Since the question asks for the answer to be in terms of