Circumference of Circle

beginnergeometrycircles

Calculates the perimeter (distance around) a circle

The Formula

C = 2πr

Variables & Symbols

C

Circumference

Unit: units

r

Radius

Unit: units

π

Pi (≈3.14159)

When to Use This Formula

  • Finding distance around a circle
  • Calculating wheel rotations
  • Track and racing calculations
  • Manufacturing circular objects

Worked Examples

Example 1

Problem:

Find circumference with radius 7

Solution: C ≈ 43.98 units

Step-by-Step:

1

Apply formula: C = 2π × 7

2

Calculate: C = 14π

3

C ≈ 43.98 units

Common Mistakes to Avoid

  • Confusing with area formula
  • Using diameter when formula requires radius
  • Forgetting the factor of 2

Real-World Applications

1

Tire and wheel measurements

2

Running track distances

3

Belt and pulley calculations

4

Orbital mechanics

Practice Problems

Problem 1: radius = 5

Show Answer

Answer: C ≈ 31.42 units

Problem 2: diameter = 12

Show Answer

Answer: C ≈ 37.70 units

Related Formulas

circle area formula

View Formula →

circle diameter

View Formula →

Tags:

geometrycirclecircumferenceperimeter

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