Circle Geometry

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

• A = 2πr

• A = πd

• A = r^2

• A = πr^2

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

• 15π cm

• 25π cm

• 20π cm

• 10π cm

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

• pi * radius

• pi * diameter

• 2 * pi * radius

• 2 * radius

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

• 144π cm^2

• 24π cm^2

• 36π cm^2

• 72π cm^2

What is the ratio of the circumference of a circle to its diameter?

• 2

• 4

• pi (π)

• 3

If the radius of a circle is 8 cm, what is its area?

• 128π cm^2

• 16π cm^2

• 64π cm^2

• 32π cm^2

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

• radius / 2

• radius + radius

• 2 * radius

• radius * 2

If the area of a circle is 64π cm², what is its radius?

• 4

• 16

• 8

• 32

If the circumference of a circle is 18π cm, what is its diameter?

• 9 cm

• 36 cm

• 18 cm

• 12 cm