Question 1

What is Pi (π)?

Accepted Answer

Pi (π) is a mathematical constant representing the ratio of a circle's circumference to its diameter. It is an irrational number, meaning its decimals go on infinitely without repeating. For basic calculations, it is commonly approximated as 3.14159.

Question 2

What is the formula for the Area of a Circle?

Accepted Answer

The formula for the area of a circle is A = πr², where 'A' is the Area, 'π' is Pi, and 'r' is the radius of the circle. This means the area is equal to Pi multiplied by the radius squared.

Question 3

How do I find the Radius if I have the Diameter?

Accepted Answer

The diameter is simply a straight line extending from edge to edge passing through the exact center of the circle. The radius extends from the center to the edge. Therefore, the radius is always exactly half of the diameter (r = d / 2).

Question 4

How do I find the Area if I only have the Circumference?

Accepted Answer

First, find the radius from the circumference formula (C = 2πr), which means r = C / (2π). Once you have the radius, you can plug it into the standard area formula A = πr².

Question 5

Why is the Area in 'square' units?

Accepted Answer

Area measures the two-dimensional space inside a shape. When you multiply the radius mapping one dimension by the radius mapping the second dimension (r * r or r²), the resulting units are also squared (e.g., cm * cm = cm²).

Area of a Circle Calculator

Circle Properties

The Geometry Formulas

Frequently Asked Questions

Share With Your Class

Related Calculators