Geometry Circumference

What is the circumference of a circle with a radius of 21 cm?

• 42π cm

• 21π cm

• 110.25π cm

• 441π cm

What is the formula to find circumference?

•  $c=2\pi r$  

If the circumference of a circle is 28π, what is the radius of the circle?

• 28

• 14

• 56

• 196

What is the radius of this circle?

• 18

• 36

• 9

• 8

A cruise ship has a large, circular window. It has a diameter of 6 meters. What is the window's approximate circumference?

• 3 m

• 3π m

• 12 m

• 6π m

A DVD has a diameter of 15 millimeters. Which equation would help you determine the circumference?

• c = 15π

• c = 2π15

• c = π(15²)

• c = π(7.5²)

What does perimeter mean?

• the amount of space inside a shape

• the amount of space inside a shape divided by two

• the distance around the shape

• half the distance around a shape

What is the circumference of a circle with a diameter of 6.33 ft? 

• 19.89 ft

• 39.77 cm

• 6.33 m

• 19.88 mi

What is the circumference of a circle with a radius of 3.72 in? 

• 23.37 in

• 35.17 in

• 28.67 in

• 23.36 in

A circular swimming pool is 21 feet in diameter. What is the circumference of the pool?

• 10.5 ft

• 42 ft

• 65.97 ft

• 131.95 ft