Circles

What is the formula for circumference of a circle given the diameter?

• C = π r
• C = 2 π r
• C = π d
• C = 2 π d

The distance across a circle through its center is called the _____.

• diameter
• radius
• π
• center

A _____ is half of a circle.

• circumference
• pi
• semicircle
•  composite figure

If you are given the diameter, how can you calculate the radius?

• Multiply the diameter by 2
• Divide the diameter by 2
• Add 2 to the diameter
• Subtract 2 from the diameter

Which segment is the diameter?

• AC
• BD
• LM
• CE

Find the radius of the circle

• 20 ft

• 10 ft

• 5.5 ft

• 10

find the diameter of the circle

• 14 m

• 7 m

• 14

• 3.5 m

find the diameter of the circle

• 1 ft

• 4 ft

• 4 mm

• 2 ft

what is this shape called

• circle

• semi circle

• moon

• triangle

what is the radius of the inner circle?

• 12 in

• 8 in

• 8 ft

• 4 in