Circles & Circumference

Understand circle properties, circumference, area, and real-world applications.

7th Grade

Geometry

~45 min

🎮 Interactive Activity: Circumference Calculator

Calculate the circumference of a circle!

Circle with radius 5

🎮 Interactive Activity: Circle Area Calculator

Calculate the area of a circle!

Circle with radius 4

1. Circle Basics

Parts of a Circle

A circle is a set of points equidistant from a center point.

Key Terms:

• Radius (r): Distance from center to edge

• Diameter (d): Distance across through center, d = 2r

• Circumference (C): Distance around the circle

• Area (A): Space inside the circle

The Number π (Pi):

π (pi) is approximately 3.14. It's the ratio of a circle's circumference to its diameter. For any circle, C ÷ d = π.

2. Circumference

3. Area of a Circle

4. Real-World Applications

5. Problem-Solving Strategies

6. Common Errors & Tips

Frequently Asked Questions

Practice Time!

Practice Quiz

Questions

Correct

Score

What is the circumference of a circle with radius 5? (Use π ≈ 3.14)

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What is the area of a circle with radius 4? (Use π ≈ 3.14)

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If the diameter of a circle is 10, what is the radius?

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What is the circumference of a circle with diameter 8? (Use π ≈ 3.14)

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What is the area of a circle with diameter 6? (Use π ≈ 3.14)

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If the circumference is 31.4, what is the radius? (Use π ≈ 3.14)

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What is π (pi) approximately equal to?

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A circle has radius 7. What is its area? (Use π ≈ 3.14)

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What is the relationship between diameter and radius?

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If a circle's area is 78.5, what is its radius? (Use π ≈ 3.14)

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