Circles

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

• radius * radius

• 2 * pi * radius

• pi * radius

• 2 * radius

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

• 10π cm

• 25π cm

• 20π cm

• 15π cm

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

• A = 2πr

• A = πr^3

• A = πr^2

• A = πr

If the radius of a circle is 3.5 cm, what is its area?

• 38.465 cm^2

• 12.25 cm^2

• 7.07 cm^2

• 21.98 cm^2

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

• 18 cm

• 24 cm

• 37.7 cm

• 30 cm

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

• 10 cm

• 4 cm

• 6 cm

• 2 cm

If the circumference of a circle is 18.84 cm, what is its diameter?

• 12 cm

• 9 cm

• 6 cm

• 3 cm

If the area of a circle is 154 cm², what is its radius?

• 7 cm

• 5 cm

• 10 cm

• 12 cm

If the circumference of a circle is 31.42 cm, what is its radius?

• 10 cm

• 5 cm

• 7 cm

• 3 cm

If the area of a circle is 78.5 cm², what is its diameter?

• 10 cm

• 20 cm

• 15 cm

• 5 cm