Circle Calculator
Calculate all properties of a circle from any one measurement.
Radius
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Diameter
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Circumference
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Area
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Circle Formulas
Area = πr² = π(d/2)²
Circumference = 2πr = πd
Key Relationships
- Diameter = 2 × Radius
- Radius = Diameter ÷ 2
- Circumference = π × Diameter
- Area = π × Radius²
π (pi) ≈ 3.14159265359...