Properties of Circles

What is the formula for the circumference of a circle?

• π * r

• r^2

• 2 * r

• 2 * π * r

What is the formula for the area of a circle?

• A = 2πr

• A = πr^2

• A = r^2

• A = 0.5πr^2

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

• 3 cm

• 15 cm

• 8 cm

• 10 cm

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

• The radius and diameter of a circle have no relationship

• The diameter is always half the length of the radius

• The radius and diameter of a circle are always equal

• The relationship between the radius and diameter of a circle is that the diameter is always twice the length of the radius.

What is the measure of the central angle of a circle if it subtends an arc of 60 degrees?

• 30 degrees

• 60 degrees

• 90 degrees

• 45 degrees

What is the relationship between the radius of a circle and the length of an arc?

• The radius of a circle has no effect on the length of an arc.

• The radius of a circle and the length of an arc are inversely proportional.

• The relationship between the radius of a circle and the length of an arc is that they are directly proportional.

• The length of an arc is always equal to the circumference of the circle.

If the radius of a circle is 8 cm, what is the area of the sector formed by a central angle of 45 degrees?

• 16π

• 4π

• 8π

• 32π

What is the formula for the length of an arc in a circle?

• L = πr(θ/180)

• L = 2r(θ/360)

• L = 2πr(θ/360)

• L = 2πr(θ/180)

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

• The circumference of a circle is inversely proportional to the radius.

• The circumference of a circle is equal to the radius.

• The circumference of a circle is not related to the radius.

• The circumference of a circle is directly proportional to the radius.

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

• 8 cm

• 6 cm

• 10 cm

• 4 cm