Circle Circumference Quiz

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

• 2 * π * r

• π * r

• 2 * r

• r^2

Answer explanation

The formula to calculate the circumference of a circle is 2 * π * r, where r is the radius of the circle.

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

• 8.5 cm

• 31.42 cm

• 25.12 cm

• 15.7 cm

Answer explanation

The circumference of a circle is calculated using the formula C = π * d, where d is the diameter. Substituting d = 10 cm, C = π * 10 = 31.42 cm. Therefore, the correct answer is 31.42 cm.

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

• 7.5 cm

• 15.70795 cm

• 20 cm

• 31.4159 cm

Answer explanation

The circumference of a circle is calculated using the formula 2 * π * radius. Substituting the radius (5 cm) into the formula gives 2 * π * 5 = 31.4159 cm. Therefore, the correct answer is 31.4159 cm.

How do you calculate the circumference of a semi-circle?

• Circumference of a semi-circle = (2 * π * r) / 2 = π * r

• Circumference of a semi-circle = 2 * r

• Circumference of a semi-circle = π * r / 2

• Circumference of a semi-circle = 2 * π * r

Answer explanation

To calculate the circumference of a semi-circle, you use the formula (2 * π * r) / 2 = π * r, which simplifies to π * r.

What is the formula to find the circumference of a quarter circle?

• (π * diameter) / 4

• (2 * π * radius) / 2

• (π * radius) ^ 2

• (π * radius) / 2

Answer explanation

The formula to find the circumference of a quarter circle is (π * radius) / 2.

Calculate the circumference of a circle with a diameter of 14 cm.

• 21π cm

• 28π cm

• 14π cm

• 7π cm

Answer explanation

The circumference of a circle is calculated using the formula C = π * d, where d is the diameter. Substituting d = 14 cm, we get C = π * 14 = 14π cm. Therefore, the correct answer is 14π cm.

Find the circumference of a circle with a radius of 8 cm.

• 64 cm

• 50.26544 cm

• 12.56 cm

• 25.13272 cm

Answer explanation

The circumference of a circle is calculated using the formula 2 * π * radius. Substituting the radius (8 cm) into the formula gives 2 * 3.14159 * 8 = 50.26544 cm.

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

• 24π cm

• 18π cm

• 6π cm

• 12π cm

Answer explanation

The circumference of a semi-circle is half the circumference of a full circle, which is π times the diameter. Therefore, the circumference of a semi-circle with a diameter of 12 cm is 6π cm.

If the radius of a semi-circle is 6 cm, what is its circumference?

• 12π cm

• 6π cm

• 36 cm

• 18 cm

Answer explanation

The circumference of a semi-circle is π times the diameter, which is twice the radius. Therefore, the circumference is 2 * 6π = 12π cm, but since it's a semi-circle, the correct answer is 6π cm.

Calculate the circumference of a quarter circle with a radius of 10 cm.

• 12.56637 cm

• 25.13274 cm

• 15.70796 cm

• 18.84956 cm

Answer explanation

The circumference of a quarter circle is 1/4 of the circumference of a full circle. Circumference = 2 * π * radius. Therefore, 1/4 * 2 * π * 10 = 15.70796 cm.