Circles: Circumference Review

What is the formula for finding the circumference of a circle in terms of the diameter?

• Circumference = 2 * pi * radius

• Circumference = pi * diameter

• Circumference = 2 * pi * diameter

• Circumference = 2 * diameter

What is the formula for finding the circumference of a circle in terms of the radius?

• Circumference = 2 * pi * diameter

• Circumference = 2 * diameter

• Circumference = pi * diameter

• Circumference = 2 * pi * radius

Find the circumference of the circle.

• 31.4 cm

• 78.5 cm

• 314 cm

• 15.7 cm

Daniel wants to buy cookies for her 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 

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

Find the circumference (to the nearest whole number)

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

Jayne has a very large circular lollipop that has a circumference of 25.12 inches. What would the diameter of Jayne’s lollipop be? Use π = 3.14.

• 4 in.

• 8 in.

• 12 in.

• 16 in.

What is the perimeter of a semicircle with a radius of 10 centimeters?

• 47.13 centimeters

• 62.83 centimeters

• 15.71 centimeters

• 31.42 centimeters

Circumference = 34.54 cm

Calculate the diameter of the circle.

Serena drew a circle with a circumference of 157 centimeters. What is the approximate diameter of the circle she drew?

• 1.57 cm

• 15.7 cm

• 50 cm

• 25 cm