Perimeter of Regular Polygon

Theorem
Let $P$ be a regular $n$-sided polygon whose side length is $b$.

Then the perimeter $L$ of $P$ is given by:
 * $L = n b$

Proof
By definition, an $n$-sided polygon has $n$ sides.

By definition, a regular polygon has sides all the same length.

By definition, the perimeter of a polygon is the total length of all its sides.

Thus $P$ has $n$ sides all of length $b$.

Hence $L = n b$.