Circle Concepts

What is the formula to calculate the circumference of a circle?

• 2 * π * r^2

• 3 * π * r

• π * r^2

• 2 * π * r

If the radius of a circle is 5 cm, what is its circumference? (Use π=3.14)

• 25 cm

• 31.4 cm

• 10 cm

• 15.7 cm

What is the formula to find the area of a circle?

• πr^2

• 2r^2

• πr

• 2πr

If the diameter of a circle is 12 cm, what is its area? (Use π=3.14)

• 75.36 cm²

• 9.42 cm²

• 113.04 cm²

• 24 cm²

What is the name of the line segment that passes through the center of the circle and has its endpoints on the circle?

• tangent

• chord

• radius

• diameter

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

• The diameter is always equal to the length of the radius.

• The diameter is always half the length of the radius.

• The diameter and radius have no relationship.

• The diameter is always twice the length of the radius.

If the circumference of a circle is 31.4 cm, what is its diameter? (Use π=3.14)

• 15 cm

• 25 cm

• 20 cm

• 10 cm

What is the name of the distance across a circle through its center?

• radius

• perimeter

• circumference

• diameter

Solve the following word problem: A circular garden has a circumference of 50 meters. What is the radius of the garden? (Use π=3.14)

• 25 meters

• 7.96 meters

• 5.5 meters

• 12.5 meters

Solve the following word problem: A bicycle wheel has a diameter of 26 inches. What is its circumference? (Use π=3.14)

• 37.2 inches

• 81.64 inches

• 52.36 inches

• 64.78 inches