Skip to lesson

Choose “Save as PDF” in the print dialog to keep a copy.

Cogito

Integrated Math 2 · Chapter 6 · Lesson 1

Practice Worksheet

Circumference, Area, and Arcs

Measuring a circle and a piece of one.

12 problems · about 21 minutes · G-C.B.5, G-GMD.A.1

NameDate

Figure — use these to answer the problems

Change the radius and watch the circumference follow. Their ratio to the diameter never moves.
d = 8
  • Diameter8 cm
  • Circumference25.13 cm
  • Circumference ÷ diameter3.14
Radius4
Figure 1

Warm Up

Straightforward practice. Get the method working first.

5 problems

  1. Radius 7. What is the area divided by π?

    Answer

  2. How can you tell which formula gives area?

    • Area is in square units, so it uses a squared length.
    • Area is always the larger number.

  3. Radius 5. Circumference divided by π?

    Answer

  4. Radius 5. Area divided by π?

    Answer

  5. Diameter 12. What is the radius?

    Answer

Build It Up

The same ideas with more to keep track of.

3 problems

  1. A 90° sector is what fraction of the circle, as a decimal?

    Answer

  2. A 120° sector is what fraction, to three decimal places?

    Answer

  3. Radius 6, 180° sector. Arc length divided by π?

    Answer

Stretch Yourself

Mixed problems. Work out what kind of question it is before you start.

4 problems

  1. Sort each formula by what it measures.

    Write each item under the heading it belongs to: Two pi r · Arc length · Pi r squared · Sector area

    Measures a length

    Measures an area

  2. Radius 3. Area divided by π?

    Answer

  3. The Circumference

    A circle has radius 10. What is the circumference divided by π?

    Answer

  4. The Area

    Same circle. What is the area divided by π?

    Answer