4-2: Circumference of a Circle

Key Concept

Circumference is the distance around a circle.

Exploring circumference Look for a pattern.

Three circles.

Find a relationship between the distance around and the distance across a circle to determine an approximate formula for circumference.

The circumference of a circle is about three times its diameter. You can use this information to estimate an answer.

Π (π) is the ratio of a circle's circumference C to its diameter d.

Approximations for pi (π) π is a nonterminating and nonrepeating decimal. Both 3.14 and 22/7 are good approximations for π.

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Table of Contents

Digits, Grade 7, Volume 1, Homework Helper Unit A: Number and Operations Unit B: Expressions, Equations, and Relationships Unit C: Measurement and Geometry Unit D: Proportionality English/Spanish Glossary Formulas Math Symbols Formulas Measures Properties