What is the circumference of the circle below in terms of pi (π)?
(a) πr²       (b) 2πr      (c) πr

Solution:

The circumference of a circle is the perimeter of the circle. It is the total length of the boundary of the circle.

(a) πr² is used to calculate the area of a circle, where r is the radius.

(b)  2πr is used to calculate the circumference of a circle, where r is the radius.

(c)  πr is used to calculate the circumference of a semi-circle, where r is the radius.

Thus, the formula to calculate the circumference of a circle is option (b) 2πr

What is the circumference of the circle below in terms of pi (π)?

Summary:

The circumference of a circle can be calculated using the expression (b) 2πr