4.4.4

Area of a Circle

Test yourself

Circle Formulae

There are standard formulae for the area and circumference of a circle.

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Area

  • The area of a circle is given by A = πr2.
  • π is the circle constant called ‘pi’ and is roughly 3.142.
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Circumference

  • The circumference of a circle is its perimeter:
    • Circumference = 2πr = πd
  • Where d is the diameter or r is the radius.

Jump to other topics

1Number

1.1Using Numbers

1.2Fractions, Decimals & Percentages

1.3Powers & Roots

1.4Accuracy

2Algebra

2.1Introduction to Algebra

2.2Manipulating Algebra

2.3Proofs & Functions

2.4Straight Line Graphs

2.5Common Graphs

2.6Transformations & Tangents

2.7Properties of Graphs

2.8Solving Equations

2.9Inequalities

2.10Sequences

3Ratio

4Geometry

4.1Introduction to Geometry

4.2Triangles & Quadrilaterals

4.3Transformations

4.4Circle Basics

4.5Circle Theorems

4.6Measurements & Units

4.7Calculating Area

4.8Triangle Formulae

4.93D Shapes

4.10Vectors

5Probability

6Statistics

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