We call that word the circumference of the circle. Now, we know how the diameter and the radius relates, but how does the circumference relate to, say, the diameter.

Find the circumference of a circle when given either the radius or diameter. Find the radius or diameter of a circle when given the circumference.

What is circumference? Circumference is the distance around the outside of a circle (its perimeter!). Want a review of circle vocabulary terms (like pi, radius, and diameter)? Check out …

Let's see if we can figure out, given that its circumference is 6 pi of these units, what is the area going to be equal to? Pause this video and see if you can figure it out on your own.

Learn how the number Pi allows us to relate the radius, diameter, and circumference of a circle.

Learn how to find the circumference, the distance around a circle, when given the area.

Just as we said that the circumference could be written as two pi r or as pi times two r, two r is just the diameter. So, we could say that the circumference is equal to pi times the diameter.

It takes 2 π radians (a little more than 6 radians) to make a complete turn about the center of a circle. This makes sense, because the full circumference of a circle is 2 π r , or 2 π radius …

Learn the relationship between the radius, diameter, and circumference of a circle.

What is circumference? Circumference is the distance around the outside of a circle (its perimeter!). Want a review of circle vocabulary terms (like pi, radius, and diameter)? Check out …