Circumference and Area of Circles

The video tutorial covers the application of circumference in geometry. It begins with a quick poll to find the radius of a circle given its circumference. The lesson progresses to measuring the perimeter of a wire picture frame by understanding circle properties. The wire is then conceptually stretched into a circle to calculate its radius. The session concludes with a summary and a cool down exercise comparing the circumferences of two circles.

What is the formula to find the radius if the circumference of a circle is known?

• Divide the circumference by 2 and multiply by pi

• Multiply the circumference by 2 and divide by pi

• Divide the circumference by 2 and pi

• Multiply the circumference by pi and divide by 2

If a rectangle is 8 inches by 10 inches, what is the perimeter of the wire used to frame it?

• 20 inches

• 28 inches

• 18 inches

• 36 inches

How many full circles can be formed from 14 half circles?

• 14 full circles

• 10 full circles

• 7 full circles

• 5 full circles

What is the total circumference of 10 full circles if each circle has a diameter of 2 inches?

• 10 pi inches

• 30 pi inches

• 40 pi inches

• 20 pi inches

If a wire is stretched to form a complete circle with a circumference of 62.8 inches, what is the radius?

• 20 inches

• 5 inches

• 15 inches

• 10 inches

What is the relationship between the diameter and the radius of a circle?

• The diameter is equal to the radius

• The diameter is twice the radius

• The diameter is half the radius

• The diameter is three times the radius

Circle A has a diameter of 9 cm, and Circle B has a radius of 5 cm. Which circle has a larger circumference?

• Circle B

• Both have the same circumference

• Circle A

• Cannot be determined

How many centimeters larger is the circumference of Circle B compared to Circle A?

• 4 pi centimeters

• 3 pi centimeters

• 2 pi centimeters

• pi centimeters

What is the circumference of Circle A if its diameter is 9 cm?

• 18 pi cm

• 9 pi cm

• 27 pi cm

• 36 pi cm

What is the circumference of Circle B if its radius is 5 cm?

• 15 pi cm

• 10 pi cm

• 5 pi cm

• 20 pi cm