## How to find out the circumference of a circle

Let's draw a regular polygon (inscribed polygon and circumscribed polygon) surrounding a circle.

The perimeter of an inscribed polygon is less than the perimeter of the circle, and the perimeter of an inscribed polygon is greater than the perimeter of the circle.

After all, it can be said that the circumference of a circle is the value between the inscribed and circumscribed polygons.

As the number of vertices of the polygon increases, the difference in the two polygons' circumference gradually decreases. When n = ∞, the length of the two polygons is the same as the circle's length.