Radius and Diameter of Circles

If the diameter of a circle is 16 cm, what is the radius?

• 6 cm

• 7 cm

• 8 cm

• 9 cm

If a circle has a radius of 12 cm, what is its diameter?

• 20 cm

• 22 cm

• 24 cm

• 26 cm

If the radius of a circle is 18 cm, what is the diameter?

• 24 cm

• 30 cm

• 36 cm

• 40 cm

True or False: The radius can be longer than the diameter of a circle.

• True

• False, the radius is always half the length of the diameter.

• The radius can be equal to the diameter.

• The radius is twice the length of the diameter.

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

• 3 cm

• 4 cm

• 5 cm

• 6 cm

What is the relationship between radius and diameter?

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

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

• The diameter is equal to the radius.

• The radius and diameter are the same length.

How do you calculate the circumference of a circle using the radius?

• C = π * radius^2

• C = 2 * π * radius

• C = π * diameter

• C = radius^2 * 2 * π

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

• A = π * radius²

• A = (π/4) * diameter²

• A = 2 * π * diameter

• A = π * diameter

What is the diameter of a circle if the radius is 7 cm?

• 10 cm

• 12 cm

• 14 cm

• 16 cm

What is the formula for the area of a circle using the radius?

• A = π * radius²

• A = 2 * π * radius

• A = π * radius

• A = radius²