Calculating Circumference from Radius

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

• Circumference = pi * d

• Circumference = pi * r^2

• Circumference = 2 * pi * r

• Circumference = 2 * r

Which formula is used if only the radius of the circle is known?

• Circumference = 2 * r

• Circumference = 2 * pi * r

• Circumference = pi * r^2

• Circumference = pi * d

How does the formula for circumference change when using the diameter instead of the radius?

• Add pi to the diameter

• Divide the diameter by pi

• Multiply pi by twice the radius

• Multiply pi by the diameter

What does pi represent in the context of a circle?

• The area of the circle

• The ratio of a circle's circumference to its diameter

• The radius of the circle

• The diameter of the circle

Why is pi considered a constant?

• It varies with the size of the circle

• It is different for each circle

• It is the same for all circles

• It changes based on the radius

If the radius of a circle is 9 cm, what is the circumference in terms of pi?

• 18 pi cm

• 9 pi cm

• 27 pi cm

• 36 pi cm

What is the result of the circumference calculation in terms of pi for a radius of 9 cm?

• 27 pi cm

• 9 pi cm

• 36 pi cm

• 18 pi cm

How do you calculate the circumference using an approximate value of pi?

• Multiply the diameter by 3.14

• Multiply the radius by 2 and then by 3.14

• Divide the diameter by 3.14

• Add 3.14 to the radius and multiply by 2

What is the approximate decimal value of the circumference when the radius is 9 cm?

• 37.68 cm

• 18.84 cm

• 56.52 cm

• 28.26 cm

What is the purpose of using the approximate value of pi in calculations?

• To get an exact result

• To simplify the calculation

• To get an approximate result

• To increase calculation time