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

*To find the diameter, measure the circle from its left-right points [divide the circle in half and measure the line you made, make sure the line is straight]. Suppose you get 10in, that is your …

And so when we think about area, we know that the area of a circle is equal to pi times the radius of the circle squared. And you say, well, they gave us the diameter.

The diameter of the circle is equal to what? 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.

A circle has a circumference of 113.04 units. What is the diameter of the circle? Use 3.14 for π and enter your answer as a decimal.

Let's say that we have a circle that has a diameter of 10 centimeters. Based on that, what is the circumference of that circle going to be? Well, we can go to this right over here, and actually …

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 …

The standard form equation of a circle contains the squares of two binomials. Sometimes, we'll be asked to determine the center or radius of a circle represented by an equation in which the …

What are circles? Circles are round. They don't have any corners. All of the points on a circle are the same distance from the center. That distance is called the radius, and it's usually …

The table has the approximate circumferences and diameters of the following circles, in millimeters. Calculate the rate circumference diameter for each circle. You're welcome to split …