Geometry 2-B



Geometry Worksheet

8.9 – Circumference of Circles Name ____________________________________

1. What is the relationship between the radius and the diameter?_________________________________________

2. If the radius is 5cm, then the diameter is __________ 3. If the diameter is 14cm, then the radius is _________

4. If the radius is 3.5in, then the diameter is __________ 5. If the diameter is 11ft, then the radius is __________

Find the radius and the diameter of each circle. Include proper units!

6. 7. 8. 9.

Radius = ________ Diameter = ________ Radius = ________ Diameter = ________ Radius = ________ Diameter = ________ Radius = ________ Diameter = ________

10. What is the FORMULA for CIRCUMFERENCE of a circle? _______________

EXACT: Use the ( symbol – NOT 3.14 APPROX: Use 3.14 – NOT the ( symbol or the( key

Find the EXACT and APRROXIMATE circumference of each circle. Your answers should have plain units!

11. 12. 13. 14.

Radius = ________ Diameter = ________ Radius = ________ Diameter = ________ Radius = ________ Diameter = ________ Radius = ________ Diameter = ________

EXACT Circumference _______________ EXACT Circumference _______________ EXACT Circumference _______________ EXACT Circumference ________

APPROX. Circumference _______________ APPROX. Circumference _______________ APPROX. Circumference _______________ APPROX. Circumference_______

15. Radius = 13cm 16. Radius = 7in 17. Diameter = 6ft 18. Diameter = 16mm

EXACT Circumference _______________ EXACT Circumference _______________ EXACT Circumference _______________ EXACT Circumference ________

APPROX. Circumference _______________ APPROX. Circumference _______________ APPROX. Circumference _______________ APPROX. Circumference_______

Given the CIRCUMFERENCE, WORK BACKWARDS using the formula to find the radius.

19. Circum = 20( cm. 20. Circum = 10( in. 21. Circum = 94.2 ft. 22. Circum = 15.70 cm.

Radius = ________ Radius = ________ Radius = ________ Radius = ________

|23. Find the approximate circumference of a circle with diameter = 10cm |24. Find the approximate circumference of a circle with radius = 5cm |

|25. Find the exact circumference of a circle with radius = 3cm |26. Find the exact circumference of a circle with diameter = 12cm |

27. State the FORMULA for finding ARC LENGTH:

Use the formula to find each arc length.[pic]

28. 29. 30. 31.

d = _____ d = _____ d = _____ d = _____

Circumference ________ Circumference ________ Circumference ______________ Circumference ______

Fraction of circle highlighted _______ Fraction of circle highlighted _______ Fraction of circle highlighted _______ Fraction of circle highlighted ___

Arc Length _______ Arc Length _______ Arc Length _______ Arc Length _______

32. The Ferris Wheel has a radius of 18ft.

A. What is the diameter? _____________

B. Calculate the approximate circumference. ______________

C. If there are nine chairs on the ferris wheel, what is the arc length between each chair? ______________

33. A birthday cake is sliced into 8 equal pieces. The arc length of one piece of cake is 6.28 inches as shown.

Find the diameter of the cake.

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