Circle Terminology

CircleThe set of points in a plane that are a fixed distance from a given point called the center of the circle.

A circle is labeled by its center.

Circle A

A

B

Circle B

C

Circle C

Chord

• A segment joining two points on a circle

• Example: ABB

CAA

B

Diameter

• A chord that passes through the center of a circle.

• Example: ABO

A

B

A

B

Name the following:

, or GO

What is the relationship between the radius and the diameter?

If you said:

The diameter is twice the radius.

The radius is half of the diameter.

You are absolutely correct.

What is the………

Radius = 7 cm

Diameter = 14 cm

Radius = 13 km

Diameter = 26 km

1. What circle has a diameter of 7 mm?2. What circle has a radius of 7 km?3. What circle has a diameter of 8 m?4. What circle has a radius of 12 m?5. If the circles were drawn to scale, which circle would be the smallest?

1. What circle has a diameter of 7 mm? Circle J2. What circle has a radius of 7 km? Circle B3. What circle has a diameter of 8 m? Circle E4. What circle has a radius of 12 m? Circle G5. If the circles were drawn to scale, which circle would be the smallest? Circle J