1. What is the Circumference Formula?

The circumference of a circle is the linear distance around its edge. It's calculated using the formula C = 2πr, where r is the radius of the circle and π (pi) is a mathematical constant approximately equal to 3.14159.

2. How Does the Calculator Work?

The calculator uses the circumference formula:

Where:

• \( C \) — Circumference (length units)
• \( r \) — Radius of the circle (length units)
• \( \pi \) — Mathematical constant (~3.14159)

Explanation: The formula shows that circumference is directly proportional to the radius, with 2π being the constant of proportionality.

3. Importance of Circumference Calculation

Details: Calculating circumference is fundamental in geometry, engineering, and various practical applications like construction, manufacturing, and physics problems involving circular motion.

4. Using the Calculator

Tips: Simply enter the radius of your circle in any length unit. The result will be in the same units. The radius must be a positive number.

5. Frequently Asked Questions (FAQ)

Q1: What if I know the diameter instead of radius?
A: The diameter is twice the radius (d = 2r), so you can divide the diameter by 2 before using this calculator.

Q2: What's the value of π used in calculations?
A: The calculator uses PHP's built-in pi() function which provides π to about 14 decimal places (3.1415926535898).

Q3: Can I use this for partial circles (arcs)?
A: No, this calculates full circumference. For arc length, you'd need the central angle as well.

Q4: What units should I use?
A: Any consistent length unit (meters, inches, feet, etc.). The result will be in the same units as your input.

Q5: How accurate is this calculation?
A: Extremely accurate, limited only by floating-point precision in computers (about 14-15 significant digits).