Circumference

Circumference can be thought of as the "perimeter" of a circle or the distance around a circle. Since pi is the ratio of circumference to diameter, circumference can be calculated by multiplying the circle's diameter by pi. Another formula substitutes d = 2r, where one diameter equals two radii, and C = 2(r)(pi). Related topics include area of a circle, arc length, and parts of a circle.

Videos

$How to calculate the circumference of a circle.$
$How to calculate the circumference of a circle given diameter or radius.$
$How to find the radius of a circle given circumference.$
$How to find the perimeter of a figure that appears to be a track.$
$How to find the circumference of a figure formed by two different circles and a straight line.$