1. What is Radius from Circumference?

The radius is the distance from the center of a circle to any point on its edge. Calculating it from the circumference (the distance around the circle) is a fundamental geometric operation.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( r \) — Radius of the circle
• \( c \) — Circumference of the circle
• \( \pi \) — Mathematical constant (approximately 3.14159)

Explanation: Since circumference \( c = 2\pi r \), we can rearrange the formula to solve for radius.

3. Importance of Radius Calculation

Details: Knowing the radius is essential for many geometric calculations including area calculation, arc length determination, and in various engineering and design applications.

4. Using the Calculator

Tips: Enter the circumference in any units (must be greater than 0). The result will be in the same units.

5. Frequently Asked Questions (FAQ)

Q1: What if my circumference is in inches?
A: The radius result will also be in inches. The calculator preserves the units you input.

Q2: How precise is this calculation?
A: The calculation uses PHP's pi() function which provides sufficient precision for most practical applications.

Q3: Can I use this for spheres?
A: This calculates the radius of a circle. For a sphere's radius from its circumference, the same formula applies.

Q4: Why is pi used in the formula?
A: Pi (π) is the fundamental constant relating a circle's circumference to its diameter (and thus radius).

Q5: What's the maximum value I can enter?
A: The calculator accepts any positive number up to PHP's floating point maximum (about 1.8e308).