1. What is the Circle Area Formula?

The area of a circle is calculated using the formula A = πr², where A is the area and r is the radius of the circle. This fundamental geometric formula is used in many practical applications.

2. How Does the Calculator Work?

The calculator uses the circle area formula:

Where:

• \( A \) — Area in square feet
• \( \pi \) — Mathematical constant (~3.14159)
• \( r \) — Radius in feet

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

3. Importance of Area Calculation

Details: Calculating circular areas is essential in construction, landscaping, manufacturing, and many engineering applications where circular shapes are involved.

4. Using the Calculator

Tips: Enter the radius in feet. The radius must be a positive number. The calculator will compute the area in square feet.

5. Frequently Asked Questions (FAQ)

Q1: What if I know the diameter instead of radius?
A: Simply divide the diameter by 2 to get the radius before using the calculator.

Q2: How precise is the calculation?
A: The calculator uses PHP's built-in π constant (M_PI) which has about 14 decimal places of precision.

Q3: Can I calculate partial circles?
A: This calculator is for full circles. For sectors or segments, additional calculations are needed.

Q4: What are common uses for circle area calculations?
A: Determining material needs for circular projects, calculating coverage areas, or planning circular spaces.

Q5: How does unit conversion work?
A: This calculator works in feet. For other units, convert your measurement to feet first or adjust the result accordingly.