1. What is the Circumference Formula?

The circumference of a circle is the distance around the circle. It can be 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 of the circle.

3. Importance of Circumference Calculation

Details: Calculating circumference is fundamental in geometry, engineering, and various practical applications involving circular objects.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between radius and diameter?
A: The diameter is twice the radius (D = 2r). The formula can also be written as C = πD.

Q2: What units should I use?
A: Any length units can be used (meters, inches, feet, etc.), just be consistent.

Q3: How accurate is the π value used?
A: The calculator uses PHP's built-in pi() function which provides sufficient precision for most practical purposes.

Q4: Can I calculate radius from circumference?
A: Yes, the formula can be rearranged to r = C/(2π).

Q5: Does this work for spheres?
A: This calculates the circumference of a circle. For a sphere, you would calculate the great-circle circumference.