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Circle Calculator

Calculate radius, diameter, circumference, and area of a circle from any single measurement.

Circle Formulas

Given the radius r: diameter = 2r, circumference = 2πr, area = πr². Given the diameter d: radius = d/2. Pi (π) is approximately 3.14159265359. These formulas are fundamental in geometry, engineering, and everyday measurements.

Practical Applications

Circle calculations are used in wheel and tire sizing, pipe cross-sections, pizza sizing, landscaping (circular gardens), and any application involving round objects or circular motion.

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