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How do you find the circumference of a circle?

How do you find the circumference of a circle?. For Example. A circle has a radius of 8 centimeters. What is the circumference of the circle?. In this lesson you will learn to find the circumference of a circle by exploring the ratio of the diameter and circumference. .

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How do you find the circumference of a circle?

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  1. How do you find the circumference of a circle? For Example A circle has a radius of 8 centimeters. What is the circumference of the circle?

  2. In this lesson you will learn to find the circumference of a circle by exploring the ratio of the diameter and circumference.

  3. The Constant of Proportionality (Unit Rate) Constant of Proportionality = 3

  4. Diameter is the distance across a circle through the center. Radius is the distance from the center of the circle to the edge of the circle. d = 2r r =

  5. Springfield Middle School built a track in the shape of a circle. The diameter of the track is 100 meters. What is the circumference of the track? Circumference is the perimeter, or distance around, a circle.

  6. C = 15.7 inches C = 25.12 inches B A d = 5 inches d = 8 inches Constant of Proportionality = 3.14

  7. Pi, represented by the symbol π, is a constant ratio that relates circumference and diameter. Pi is approximated as 3.14 15.7 = 5 x 3.14 25.12 =8 x 3.14 C =πd or C = 2πr

  8. When using the radius to find the circumference, remember to multiply it by 2 to get the diameter. Wrong C = πr Correct C = 2πr

  9. What is the circumference of a circle that has a radius of 8 centimeters? Do not approximate pi. C = 2πr C = (2)π(8 cm) C = 16πcm

  10. In this lesson you have learned to find the circumference of a circle by exploring the ratio of the diameter and circumference.

  11. A circle has a radius of 6 inches. What is the circumference of the circle? Do not approximate pi.

  12. Pi is sometimes approximated as . Why is this a good approximation of pi? Explain your reasoning.

  13. Alison stated “The circumference of a circle is approximately 6 times the radius of the circle.” Is Alison’s statement correct? Explain your reasoning.

  14. A circle has a diameter of 8 meters. What is the circumference of the circle? Use 3.14 for pi. A circle has a radius of 7 feet. Find the circumference of the circle. Do not approximate pi.

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