It is the distance around the circle. The "perimeter" of the circle.

It is the distance from the center to any point in the circle.

It is an area enclosed by a chord and an arc

It is an area enclosed by two radii and an arc

It is a straight line outside the circle that touches the circumference at one point

It is a part of the circumference of any circle

It is the distance across the circle that passes through the center

It is a straight line that touches two points of the circumference but does NOT pass through the center

What does the red line represent?

The diameter of a circle is 10 in.

What is its radius?

Which ratio is used to calculate Pi?

Calculate the circumference of the circle.
C =  $$\pi$$  d

Does this circle show the radius or diameter?

According to the Area of a Circle formula, do you need to know the radius or diameter?
A =  $$\pi$$   $$r^2$$  

What is the radius of this circle?

Calculate the Area of the circle.