What is the formula to calculate the circumference of a circle using its diameter?

• Circumference = 2r

• Circumference = πd

• Circumference = 2πr

• Circumference = πr^2

What constant value is used to represent pi in calculations?

• 3.14159

• 2.71828

• 1.61803

• 6.28318

What is the relationship between the diameter and radius of a circle?

• There is no specific relationship

• The diameter is twice the radius

• The radius is twice the diameter

• The diameter is half the radius

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

• 18π cm

• 9π cm

• 36π cm

• 27π cm

Using an approximate value of pi as 3.14, what is the circumference of a circle with a radius of 9 cm?

• 56.52 cm

• 28.26 cm

• 72.68 cm

• 18.84 cm

What is the formula to calculate the circumference of a circle using its radius?

• Circumference = 2r

• Circumference = πr^2

• Circumference = 2πr

• Circumference = πd

What does the term 'in terms of pi' mean when writing the circumference of a circle?

• Ignoring the value of pi

• Writing the answer with the pi symbol

• Using pi's approximate value

• Using pi's exact value

Why do we sometimes use an approximate value of pi in calculations?

• Because pi is an irrational number

• To get a more accurate result

• Because pi is a rational number

• To simplify the calculation process

If the diameter of a circle is 12 feet, what is its circumference in terms of pi?

• 24π feet

• 36π feet

• 6π feet

• 12π feet

Using an approximate value of pi as 3.14, what is the circumference of a circle with a diameter of 12 feet?

• 37.68 feet

• 56.52 feet

• 75.36 feet

• 18.84 feet