Circle Calculator

Enter any one Value and get Other Three

Radius (R):
Diameter (D):
Circumference (C):
Area (A):
Calculate

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🔵 Circle Basics

A circle is a simple closed shape. It's all the points in a plane that are the same distance from the center point. Imagine a dot in the middle, and everything around it is the circle.

⭕ Parts of a Circle

• Center: The middle dot that's the same distance from all other points.
• Radius: The distance from the center to any point on the circle. It's half the diameter.
• Diameter: The biggest distance between any two points on the circle. Always goes through the center, and it's twice the radius.
• Circumference : The distance all the way around the circle.
• Arc: A piece of the circle.
• Major Arc: A big piece, more than half the circle.
• Minor Arc: A small piece, less than half the circle.
• Chord: A line from one point on the circle to another. If it goes through the center, it's a diameter.
• Secant: A line through the circle, touching at two points, like an extended chord.
• Tangent: A line touching the circle at just one point, the rest is outside.
• Sector: The space inside the circle, between two radii.
• Major Sector: A big piece, with a central angle over 180°.
• Minor Sector: A small piece, with a central angle under 180°.

🥧 Pi (π)

Pi is a special number (about 3.14159) that connects the circle's parts. It's the ratio of the circle's circumference to its diameter. Pi is a bit crazy because it's not a simple fraction or a repeating decimal, but it's super important in circles!

📐 Circle Formulas

Diameter (D) = 2 * Radius (R)
Circumference (C) = 2 * Pi (π) * Radius (R)
Area (A) = Pi (π) * Radius (R) * Radius (R)

📏 Where: R: Radius
D: Diameter
C: Circumference
A: Area
π: 3.14159 (Pi)