Ngữ văn 8

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

• C = π * r^2

• C = 2 * π * r

• C = 2 * r

• C = π * d

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

• 25.12 cm

• 31.42 cm

• 40.84 cm

• 15.70 cm

Calculate the circumference of a circle with a diameter of 10 m.

• 40.84 m

• 31.42 m

• 15.70 m

• 25.12 m

If the circumference of a circle is 31.4 cm, what is its radius?

• 10 cm

• 7 cm

• 5 cm

• 3 cm

A circle has a circumference of 62.8 m. What is its diameter?

• 25 m

• 15 m

• 20 m

• 30 m

How does the circumference change if the radius is doubled?

• The circumference remains the same.

• The circumference triples.

• The circumference increases by 50%.

• The circumference doubles.

If the radius is 7 inches, what is the circumference?

• Approximately 28.27 inches

• Approximately 50.24 inches

• Approximately 31.42 inches

• Approximately 43.98 inches

What is the circumference of a circle with a radius of 3.5 feet?

• 15.7 feet

• 10.5 feet

• 21.99 feet

• 28.0 feet

If a circle has a circumference of 12.56 cm, what is the radius?

• 2 cm

• 3 cm

• 5 cm

• 4 cm

Explain why the value of π is important in calculating circumference.

• π is only important in calculating the volume of a sphere.

• π is the value used to calculate the area of a circle.

• The value of π is important because it is the ratio of the circumference to the diameter of a circle.

• The value of π is irrelevant to the properties of circles.