Exploring Circumference and Area of a Circle

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

• C = 2r

• C = πd

• C = 2πr

• C = πr^2

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

• Radius is twice the diameter

• Diameter is twice the radius

• Radius is one-fourth the diameter

• Diameter equals the radius

What is pi approximately equal to?

• 3.14159

• 2.71828

• 1.61803

• 6.28318

Which of the following best describes an irrational number?

• A number that repeats its digits after a decimal point

• A number that cannot be expressed as a simple fraction

• A number that has a finite number of decimal places

• A number that can be expressed as a simple fraction

How do you calculate the circumference if the radius is given?

• C = πd

• C = 2πr

• C = πr^2

• C = r/2

What is the formula for the area of a circle?

• A = πd

• A = r^2/π

• A = 2πr

• A = πr^2

If the diameter of a circle is 10 cm, what is the radius?

• 20 cm

• 5 cm

• 2.5 cm

• 10 cm

What common mistake do students make when squaring numbers?

• Multiplying the number by 2

• Adding the number to itself

• Correctly squaring the number

• Multiplying the number by 3

If the radius of a circle is 5 cm, what is the area?

• Approximately 452 cm²

• Approximately 15.7 cm²

• Approximately 31.4 cm²

• Approximately 78.5 cm²

What does the area formula πr² imply about the units of measurement?

• Units are doubled

• Units remain the same

• Units are squared in the result

• Units are halved