Understanding Circumference of a Circle

What is the circumference of a circle?

• The radius of a circle

• The enclosing boundary of a circle

• The diameter of a circle

• The area of a circle

Which formula is used to calculate the circumference using the radius?

• C = 2r

• C = πr²

• C = 2πr

• C = πD

If the diameter of a circle is 20 cm, what is the radius?

• 10 cm

• 5 cm

• 15 cm

• 20 cm

What is the approximate value of π used in calculations?

• 3.00

• 3.14

• 3.50

• 3.75

What is the result of multiplying 3.14 by 20?

• 60.8

• 64.8

• 62.8

• 66.8

Which formula uses the diameter to find the circumference?

• C = πD

• C = 2D

• C = 2πr

• C = πr²

How does the formula C = πD simplify the calculation?

• It avoids using the diameter

• It avoids using π

• It avoids using the radius

• It avoids multiplying by 2

What is the circumference of a circle with a diameter of 20 cm using C = πD?

• 62.8 cm

• 60.8 cm

• 66.8 cm

• 64.8 cm

Why might some prefer the formula C = πD over C = 2πr?

• It uses a smaller number

• It is faster

• It is simpler

• It is more accurate

What should you not forget when stating the circumference?

• The type of circle

• The units of measurement

• The color of the circle

• The formula used