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For a circle with radius r, the area = \pi r^2 and perimeter = 2 \pi r.
On a calculator \pi \times 4.27^2 is found by π×4.27=

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## Glossary

### circle

a conic curve with equation (x-a)²+(y-b)²=r²

### union

The union of two sets A and B is the set containing all the elements of A and B.

Full Glossary List

## This question appears in the following syllabi:

SyllabusModuleSectionTopicExam Year
AQA GCSE (9-1) Foundation (UK)G: Mensuration and CalculationG17: Circles, Further and Composite ShapesCircles-
CIE IGCSE (9-1) Maths (0626 UK)4 MensurationB4.3 Calculations with CirclesCircles-
Edexcel GCSE (9-1) Foundation (UK)G: Mensuration and CalculationG17: Circles, Further and Composite ShapesCircles-
GCSE Foundation (UK)GeometryPerimeter area volumeCircles-
OCR GCSE (9-1) Foundation (UK)10: Mensuration10.03d: Area of a CircleCircles-
Universal (all site questions)PPerimeter area volumeCircles-