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:

• \( SF \) — Square feet (area)
• \( \pi \) — Mathematical constant (approximately 3.14159)
• \( r \) — Radius in feet

Explanation: The formula calculates the area of a circle by multiplying the mathematical constant π (pi) by the square of the radius.

3. Importance of Circle Area Calculation

Details: Calculating the area of a circle is essential in various fields including construction, landscaping, engineering, and mathematics. It helps determine the space occupied by circular objects or areas.

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 is the difference between radius and diameter?
A: The radius is half the diameter. The diameter is the distance across the circle through its center.

Q2: Can I use this calculator for circles in other units?
A: This calculator is specifically designed for feet. For other units, you would need to convert the radius to feet first or use a different calculator.

Q3: How accurate is the π value used in calculations?
A: The calculator uses PHP's built-in M_PI constant, which provides π with approximately 14 decimal places of precision.

Q4: What if I have the diameter instead of the radius?
A: Simply divide the diameter by 2 to get the radius before entering it into the calculator.

Q5: Can this formula be used for partial circles or sectors?
A: No, this formula calculates the area of a full circle. For partial circles or sectors, different formulas are required.