Circumference and Radius of Circles

The video tutorial explains how to find the circumference of a circle using the formula C = 2πr. It highlights the difference between radius and diameter, showing how to convert diameter to radius. The tutorial then demonstrates the calculation of circumference by substituting the radius into the formula and using the approximate value of Pi (3.14) to find the final result.

What is the formula for the circumference of a circle?

• C = πd

• C = 2r

• C = 2πr

• C = πr²

In the given problem, what measurement is provided instead of the radius?

• Diameter

• Circumference

• Area

• Volume

How do you find the radius if the diameter is given?

• Subtract 2 from the diameter

• Add 2 to the diameter

• Divide the diameter by 2

• Multiply the diameter by 2

What is the relationship between diameter and radius?

• Diameter is twice the radius

• Diameter is half the radius

• Diameter is equal to the radius

• Diameter is three times the radius

What is the formula to convert diameter to radius?

• Radius = Diameter / 2

• Radius = Diameter * 2

• Radius = Diameter - 2

• Radius = Diameter + 2

If the diameter of a circle is 14 cm, what is the radius?

• 14 cm

• 28 cm

• 21 cm

• 7 cm

What is the next step after finding the radius in the circumference formula?

• Divide by π

• Add π

• Subtract π

• Multiply by π

What is the approximate value of π used in the calculation?

• 3.50

• 3.14

• 3.00

• 3.70

How is the circumference calculated using the approximate value of π?

• By subtracting 2, π, and the radius

• By adding 2, π, and the radius

• By dividing 2, π, and the radius

• By multiplying 2, π, and the radius

What is the circumference of a circle with a radius of 7 cm using π ≈ 3.14?

• 28.00 cm

• 14.00 cm

• 43.96 cm

• 21.98 cm