1. What is Circumference?

The circumference is the distance around a circle. It's the perimeter of the circle and represents the total length of the circle's boundary.

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 circumference is directly proportional to the radius of the circle, 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 wheel design, circular construction, and more.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: Can I calculate circumference from diameter instead?
A: Yes, the formula becomes \( C = \pi d \) where d is diameter. Diameter is twice the radius.

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

Q4: How accurate is this calculation?
A: The calculation is mathematically exact, limited only by floating-point precision in computers.

Q5: Can this calculate partial circumferences?
A: No, this calculates the full circumference. For arc lengths, you'd need the central angle as well.