1. What is the Circle Area Formula?

The circle area formula calculates the size (area) of a circle using its radius. It's one of the most fundamental formulas in geometry and has applications across many fields.

2. How Does the Calculator Work?

The calculator uses the circle area formula:

Where:

• \( A \) — Area of the circle (square units)
• \( r \) — Radius of the circle (units)
• \( \pi \) — Mathematical constant (~3.14159)

Explanation: The area grows with the square of the radius, meaning doubling the radius quadruples the area.

3. Importance of Circle Area Calculation

Details: Calculating circle area is essential in fields like engineering, architecture, physics, and many real-world applications like determining material requirements or land area.

4. Using the Calculator

Tips: Enter the radius in any consistent unit (meters, inches, etc.). The result will be in square units of whatever unit you used for radius.

5. Frequently Asked Questions (FAQ)

Q1: Can I use diameter instead of radius?
A: Yes, but remember radius = diameter/2. The formula can be rewritten as \( A = \pi (d/2)^2 \) where d is diameter.

Q2: What's the value of π used?
A: The calculator uses PHP's built-in M_PI constant (approximately 3.1415926535898).

Q3: Why does area use square units?
A: Area is a two-dimensional measurement, so the units are squared (e.g., m², in²).

Q4: What if my radius is zero?
A: A radius of zero would be a single point with zero area. The calculator requires positive values.

Q5: How precise is the calculation?
A: The calculator shows results rounded to 4 decimal places, but uses higher precision for the actual calculation.