Mathematics Throughout History

The Creation of Zero and Pi

What are the measurements of a circle using pi?

There are many measurements of a circle. The perimeter of a circle is called the circumference; to calculate, multiply pi (π) times the diameter, or c = (πd), or pi (π) times twice the radius, (c = 2πr). The area (a) of a circle is calculated by multiplying pi (π) times the radius squared, or a = πr2.


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