Circumference of a Circle

Circumference of a Circle

Circumference of a Circle

• The circumference is the distance around the outside of a circle.

• Before using the formula, determine if you know the radius or the diameter.

• If you know the RADIUS - multiply 2 x pi x radius

• If you know the DIAMETER - multiply pi x diameter

• Remember to use 3.14 for pi!

Multiple Choice

What is the distance around a circle?

• Circumference
• Area
• Diameter
• Radius

Multiple Choice

Is the red line a radius or diameter of the circle?

• Radius

• Diameter

Multiple Choice

Is the red line a radius or diameter of the circle?

• Radius

• Diameter

Multiple Choice

If my radius is 10ft, what is my diameter?

• 20ft
• 5ft
• 31.4ft
• 62.8ft

Multiple Choice

Find the radius of a circle who's diameter is 40 ft.

• 40ft

• 80ft

• 20ft

• 45ft

Multiple Choice

What is the diameter of a circle with radius 1 ft?

• 1ft

• 2ft

• 3ft

Multiple Choice

Find the circumference (to the nearest whole number)

• 88 in
• 44 in
• 116 square in
• None of the above

Multiple Choice

A circle has a diameter of 17 inches. What is the circumference?

• 106.76 inches

• 53.38 inches

• 907.46 inches

• 34 inches

Multiple Choice

What is the circumference?

• 50.24
• 96
• 24
• 18

Multiple Choice

Daniel wants to buy cookies for his friend. The radius of a cookie is 5 inches. What is the cookie’s circumference?

• 10 in

• 2.5 in

• 15.7 in

• 31.4 in

Multiple Choice

Alex has trained his puppy, Popper, to jump through a ring. According to Alex's measurements and calculations, the ring has a diameter of 3.5 feet. What is the ring's circumference (use 3.14 for pi)?

• 11.32 ft
• 12.25 ft
• 10.99 ft
• 8.75 ft

Multiple Choice

A circular swimming pool is 21 feet in diameter.
How many feet around is the pool?

• 10.5 ft
• 42 ft
• 65.94 ft
• 131.95 ft

Multiple Choice

what is the circumference of this circle ?

• 3.14 cm 
• 37.68 cm
• 24 cm
• 68.4 cm