A regular polygon
is a polygon which has all its sides of equal length and all its
angles equal.

The simplest examples are an equilateral triangle
and a square. A regular polygon with n sides can be easily drawn
by starting with a circle and then drawing in radii at angles of
360^{o} ÷ n to each other. The vertices of the polygon are at
the ends of radii.

The drawings show a regular pentagon and regular
hexagon produced in this way. A regular n-sided polygon can be constructed
with compass and straightedge if and only if the odd prime factors
of n are distinct Fermat primes.

Example of a Regular Polygon: