Circle Basics
Formulas & Calculations
Real-World Circles
Missing Measurements
Challenge Problems
100

What is the term for the distance around a circle?

Circumference

100

What is the radius of a circle if the diameter is 12 cm

6cm


100

A pizza has a diameter of 14 inches. What is its radius?

7in

100

The circumference of a circle is 31.4 cm. What is its diameter?

10 cm

100

If a circle's diameter is doubled, how does the circumference change?

it also doubles

200

What is the formula for circumference using diameter?

C = πd

200

Find the circumference of a circle with a diameter of 10 cm.

31.4cm

200

A bicycle tire has a radius of 30 cm. How far does it travel in one full rotation?

188.4cm

200

The diameter of a circle is 18 inches. What is its circumference?

56.5 inches

200

A circular track has a radius of 10 m. How far does a runner travel in one lap?

62.8m

300

What is the formula for circumference using radius?

(C = 2πr)

300

If the radius of a circle is 4 cm, what is the circumference?

25.1cm
300

A clock face has a diameter of 24 cm. What is the circumference of the clock?

75.4cm

300

A circular plate has a circumference of 25 cm. What is its radius?

3.98 cm

300

A rope is shaped into a circle with a radius of 7 cm. What is its circumference?

44cm

400

What is the name of the line segment that passes through the center of a circle and touches both sides?

Diameter

400

A circular pool has a circumference of 50.24 m. What is its diameter?

16 m

400

A circular fountain has a circumference of 62.8 feet. What is its radius?

10 ft

400

The radius of a Ferris wheel is 20 meters. What is the circumference?

125.6 m

400

A circular racetrack has a radius of 50 m. If a car goes around it 5 times, what distance does it travel?

1570m

500

What is the name of the line  that goes from the centre of the circle and touches one side?

Radius