Circles: Area and Circumference Practice

What is the relationship between diameter and radius?

• The diameter is equal to the radius.

• The diameter is half of the radius.

• The diameter (d) of a circle is twice the radius: d = 2r.

• The diameter is the same as the circumference.

What is the formula for the area of a circle?

• A = πr²

• A = 2πr

• A = πd

• A = r²

What is the formula for the circumference of a circle?

• C = πd

• C = 2πr

• C = r^2π

• C = 2r

If a circular track has a circumference of 157 meters, what is the radius?

• 20 m

• 25 m

• 30 m

• 35 m

If a circular garden has a radius of 3 m, what is its circumference?

• 12.56 m

• 18.84 m

• 9.42 m

• 25.13 m

What is the circumference of a circle with a radius of 10 cm?

• 50.24 cm

• 62.8 cm

• 31.4 cm

• 78.5 cm

How do you find the radius from the circumference?

• r = C / (2π)

• r = C / π

• r = 2C / π

• r = πC

What is the area of a circle with a radius of 5 cm?

• 50 cm²

• 78.5 cm²

• 31.4 cm²

• 100 cm²

If the area of a circle is 314 cm², what is the radius?

• 8 cm

• 9 cm

• 10 cm

• 12 cm

What is the circumference of a circle with a diameter of 12 cm?

• 31.42 cm

• 37.68 cm

• 25.12 cm

• 40.84 cm