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Cogito

Grade 7 Math · Chapter 7 · Lesson 2

Practice Worksheet

Area of a Circle

A different question, with different units.

10 problems · about 18 minutes · 7.G.B.4

NameDate

Figure — use these to answer the problems

Both numbers on screen at once, with their units.
d = 8
  • Diameter8 cm
  • Circumference25.13 cm
  • Area50.27 cm²
  • Circumference ÷ diameter3.14
Radius4
Figure 1

Warm-Up Review

From earlier lessons. Loosen up before the new work.

2 problems

  1. From “Measuring a Circle”

    Diameter 50, using π = 3.14. Circumference?

    Answer

  2. From “Solving Inequalities”

    4x > 20. Smallest whole number x?

    Answer

Warm Up

Straightforward practice. Get the method working first.

4 problems

  1. Radius 4, π = 3.14. Area?

    Answer

  2. How do you tell area from circumference in a question?

    • By the units: cm² is area, cm is length.
    • By guessing which is meant.

  3. Radius 2, π = 3.14. Area?

    Answer

  4. Radius 6, π = 3.14. Area?

    Answer

Build It Up

The same ideas with more to keep track of.

2 problems

  1. Radius 5, π = 3.14. Circumference?

    Answer

  2. Which formula uses the radius squared?

    • Area.
    • Circumference.

Stretch Yourself

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

2 problems

  1. The Table

    A circle has radius 10 cm. What is its area, using π = 3.14?

    Answersquare cm

  2. The Comparison

    A circle has radius 3 cm. What is its area, using π = 3.14?

    Answersquare cm