Circles and Ratios

What is the AREA formula for a circle?

• A = πr²

• A = 2πr

• A = √π

• A = πrr

What is the CIRCUMFERENCE formula for a circle?

• C = πr²

• C = 2πr

• C = πd

• C = πrr

A circle is shown. Identify each of the following in the figure:

The center of the circle

• Point M

• Point O

• Point P

• Point N

A circle is shown. Identify each of the following in the figure:

A diameter of the circle

• Line segment MN

• Line segment MO

• Line segment NP

A circle is shown. Identify each of the following in the figure:

Three radii of the circle

• Line segment NM

• Line segment MO

• Line segment NP

• Line segment NO

Consider Circle J.

Calculate the DIAMETER of Circle J if the circumference is 100.48 centimeters.

Use 3.14 for π.

C = πd

Consider Circle J.

Calculate the CIRCUMFERENCE of Circle J when the radius is 7 meters.

Use 3.14 for π.

C = 2πr

Brianna ran 6 laps around a circular track with a diameter of 120 feet. She ran a total distance of _____ feet.

Use 3.14 for π. Round answers to the nearest hundredth.

C = πd

Consider Circle X.

Calculate the AREA of Circle X if the diameter is 13 inches.

Use 3.14 for π. Round answers to the nearest hundredth, if necessary.

A = πr² OR A = πrr

Consider Circle X.

Calculate the DIAMETER of Circle X if the circumference is 379.94 millimeters.

Use 3.14 for π.

C = πd