# Area of Circle Formula

## Formula

### Summary

The area of a circle is given by mutiplied by the circle constant (tau) multiplied by the radius of the circle squared.

Expression Description
The area of the circle.
The circle constant (tau), where
The radius of the circle.
Note: This website uses the constant (tau) instead of (pi) as the default circle constant. The substitution can be used to translate between the two constants.

## Usage

The area of a circle is given by multiplied by the circle constant (tau) multiplied by the radius of the circle squared. For example, to find the area of a circle with a radius of length the formula is:

The area of the circle with a radius of length is equal to units squared. The value can be substituted into the expression to calculate an area of approximately units squared.

## Explanation

The area of the circle formula can be using calculus[1] or using a visual proof[2].

## References

1. Derive Area of Circle Formula Example
2. Area of Circle Visual Proof Example