Calculating Circle Circumference from Diameter

What is the formula for the circumference of a circle when the diameter is known?

• Circumference = πr^2

• Circumference = πd

• Circumference = 2πd

• Circumference = 2πr

Why do we multiply by 2 in the formula Circumference = 2πr?

• To account for π being irrational

• To double the radius

• Because the diameter is twice the radius

• To simplify the calculation

Which formula would you use if only the radius of the circle is given?

• Circumference = 2d

• Circumference = 2πr

• Circumference = πd

• Circumference = πr^2

What does the constant π represent in the context of a circle?

• The area of the circle

• The radius of the circle

• The diameter of the circle

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

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

• There is no fixed relationship

• The radius is twice the diameter

• The diameter is twice the radius

• The diameter is half the radius

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

• 6π feet

• 12π feet

• 24π feet

• 36π feet

How can the circumference of a circle be approximately calculated using π as 3.14?

• Multiply the radius by 3.14

• Multiply the diameter by 3.14

• Divide the diameter by 3.14

• Add 3.14 to the diameter

How is the circumference expressed when using the exact value of π?

• As a decimal

• In terms of π

• As a fraction

• As a percentage

What is the approximate decimal value of the circumference when the diameter is 12 feet and π is taken as 3.14?

• 18.84 feet

• 24.56 feet

• 48.28 feet

• 37.68 feet

What does the squiggly equal sign represent in mathematical calculations?

• An undefined value

• An exact value

• A theoretical value

• An approximate value