1. What is the Circle Area Formula?

The circle area formula calculates the area of a circle using the radius. The formula is SF = π × r², where SF represents the area in square feet and r is the radius in feet.

2. How Does the Calculator Work?

The calculator uses the circle area formula:

Where:

• \( SF \) — Area in square feet
• \( \pi \) — Mathematical constant (approximately 3.14159)
• \( r \) — Radius in feet

Explanation: The formula squares the radius and multiplies it by π to calculate the area of a circle.

3. Importance of Circle Area Calculation

Details: Calculating the area of a circle is essential in various fields including construction, landscaping, manufacturing, and any application requiring circular surface measurements.

4. Using the Calculator

Tips: Enter the radius in feet. The value must be valid (radius > 0). The calculator will compute the area in square feet.

5. Frequently Asked Questions (FAQ)

Q1: What if I have the diameter instead of radius?
A: Divide the diameter by 2 to get the radius, then use the calculator.

Q2: Can I use different units?
A: This calculator uses feet. For other units, convert your measurement to feet first or adjust the result accordingly.

Q3: How accurate is the calculation?
A: The calculation uses PHP's built-in M_PI constant (approximately 3.1415926535898) for high precision.

Q4: What is π (pi)?
A: π is a mathematical constant representing the ratio of a circle's circumference to its diameter, approximately equal to 3.14159.

Q5: Can I calculate partial circles?
A: This calculator computes the area of a full circle. For partial circles (sectors), you would need to calculate the full area then multiply by the fraction of the circle.