Practice Maths

Parts of a Circle and Circumference — Solutions

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  1. Radius and diameter conversions

    1. r=7 cm → d:
    2. d=18 m → r:
    3. r=3.5 mm → d:
    4. d=9 km → r:
    5. r=12 cm → d:
    6. d=4.8 m → r:
    7. r=25 mm → d:
    8. d=100 m → r:

  2. Find circumference

    1. r=4 cm:
    2. r=10 m:
    3. r=3.5 cm:
    4. d=14 cm:
    5. d=8 m:
    6. r=6.2 mm:
    7. d=25 cm:
    8. r=1.5 m:

  3. Find radius or diameter from circumference

    1. C=31.42 cm → r:
    2. C=62.83 m → d:
    3. C=18 cm → r:
    4. C=44 m → d:
    5. C=100 mm → r:
    6. C=25 cm → d:
    7. C=π cm → r:
    8. C=10π m → d:

  4. Exact answers in terms of π

    1. r=6 cm:
    2. d=9 m:
    3. r=15 cm:
    4. d=7 mm:
    5. r=½ m:
    6. d=20 km:

  5. Unit conversions

    1. d=3 m → C in cm:
    2. C=1 km → r in m:
    3. Wheel r=35 cm:
    4. Semicircle d=10 cm:

  6. Real-world circumference

    1. Garden d=8 m:
    2. Bicycle wheel d=66 cm:
    3. Circles ratio 1:3, smaller C=12π cm:
    4. Running track:

  7. Circumference from diagrams Understanding

  8. Circle diagram questions Understanding

  9. Circumference table Understanding

  10. Spot the error and extended response Problem Solving