Circles: Radius, Diameter, and Circumference

Circle Vocabulary

100

Circle Terms: The distance from the center of a circle to the outside

Radius

200

Circle Terms: The longest chord in a circle that goes all the way through the middle of the circle.

Diameter

300

Circle Terms: The distance around a circle.

Circumference

400

Circle Terms: The total amount of square units inside of a circle

Area

500

Circle Terms: 3.14 or 22/7

Pi

Circumference

100

Circumference: The diameter for this circle is 10 inches

31.4 inches

200

Circumference: The diameter for this circle is 13 meters

40.82 meters

300

Circumference: The diameter of this circle is 25 yards

78.5 yards

400

Circumference: The radius for this circle is 45 centimeters

282.6 centimeters

500

Circumference: The radius for this circle is 8 mm.

50.24 mm

Area

100

Area: The radius of this circle is 2 mm

12.56 sq. mm

200

Area: The radius of this circle is 3 cm

28.26 sq. cm

300

Area: The diameter of the circle is 18 m.

254.34 sq. m

400

Area: The diameter of the circle is 6 mm.

28.26 mm

500

Area: The diameter is 15 inches.

176.625 sq in

Working Backwards

100

The circumference is 37.68 cm.  What is the radius

6 centimeters

200

Area of this circle is 254.34 inches²  What is the radius?

9 inches

300

The circumference is 15.7 inches, what is the diamter?

5 inches

400

The area of this circle is 28.26 meters²  What is the diameter?

6 meters

500

The circumference of this circle is 25.12 inches.  What is the area?

50.24 inches²