Math Grade 6-8

Math: Circles: Radius, Diameter, Circumference

Find and use circle measurements with pi

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Find and use circle measurements with pi

Math - Grade 6-8

Instructions: Read each problem carefully. Use 3.14 for pi unless the problem says otherwise. Show your work in the space provided.
  1. 1
    A circle with a radius drawn from the center to the edge.

    A circle has a radius of 6 cm. What is its diameter?

  2. 2
    A circle with a diameter drawn across the center.

    A circle has a diameter of 18 inches. What is its radius?

  3. 3
    A circle showing both the diameter and the circumference.

    A circle has a diameter of 10 meters. Find its circumference using 3.14 for pi.

  4. 4
    A circle showing a radius and highlighted circumference.

    A circle has a radius of 4 feet. Find its circumference using 3.14 for pi.

  5. 5
    A bicycle wheel with an arrow showing one full turn.

    A bicycle wheel has a diameter of 26 inches. How far does the bike move in one full turn of the wheel? Use 3.14 for pi.

  6. 6
    A round table showing circumference around the edge and diameter across the center.

    The circumference of a circular table is 94.2 inches. What is the diameter of the table? Use 3.14 for pi.

  7. 7
    A round clock face showing its diameter and outer circumference.

    The diameter of a round clock face is 12 inches. What is the circumference of the clock face? Use 3.14 for pi.

  8. 8
    A circle with highlighted circumference and a radius line.

    A circle has a circumference of 62.8 centimeters. What is its radius? Use 3.14 for pi.

  9. 9
    Two circles side by side, one showing a radius and the other showing a diameter.

    Circle A has a radius of 5 cm. Circle B has a diameter of 8 cm. Which circle has the greater circumference? Use 3.14 for pi.

  10. 10
    A circular garden with edging around the outside and a radius line.

    A circular garden has a radius of 7 meters. A gardener wants to place edging around the outside. How many meters of edging are needed? Use 3.14 for pi.

  11. 11
    A circle comparing a shorter radius with a longer diameter.

    A student says, "The radius of a circle is always longer than the diameter." Explain whether the student is correct.

  12. 12
    A circle showing its diameter and circumference.

    A circle has a diameter of 15 units. Write the circumference in terms of pi, then estimate it using 3.14 for pi.

  13. 13
    A round jar lid showing circumference and diameter.

    A jar lid has a circumference of 25.12 cm. What is the diameter of the lid? Use 3.14 for pi.

  14. 14
    A circular running track with a diameter line and a runner following the path.

    A circular running track has a diameter of 100 meters. A runner completes 3 laps. How far does the runner travel? Use 3.14 for pi.

  15. 15
    Two circles with the same center showing smaller and larger radii.

    Two circles have the same center. The smaller circle has a radius of 3 cm, and the larger circle has a radius of 9 cm. How many times greater is the larger circle's circumference than the smaller circle's circumference?

LivePhysics™.com Math - Grade 6-8

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