What Is a Dodecagon?

What twelve sides reveal

A regular dodecagon has interior angles of one hundred fifty degrees and exterior angles of thirty degrees. That makes it a strong example of how regular polygons with many sides begin to look nearly circular while still being built from straight segments.

This polygon is useful because twelve has many divisors, so the regular dodecagon supports clean symmetry arguments and partitions more readily than some other large polygons.

Because twelve divides a full turn in several familiar ways, a regular dodecagon is easy to split into halves, thirds, quarters, or six equal sections. That makes it a friendly example when students begin connecting polygon symmetry with rotations and central angles.

A dodecagon has 12 vertices, 12 sides, and 54 diagonals. Those counts come from the boundary and its connections, not from regularity. An irregular dodecagon keeps the counts even when its angles and side lengths stop matching.

The regular dodecagon's 30-degree exterior angle makes it especially convenient for rotation patterns. Twelve copies of that turn complete the circle, linking side count, symmetry, and the fixed full-turn total.

• A dodecagon is a polygon with twelve sides.
• A dodecagon has twelve sides and an interior angle sum of one thousand eight hundred degrees.
• Each interior angle of a regular dodecagon measures one hundred fifty degrees.
• A dodecagon has fifty-four diagonals in total.

Where dodecagons help

• Use dodecagon naming in side-count and polygon-angle exercises.
• Use regular dodecagons in symmetry, central-angle, and design-related problems.
• Use the figure as a high-side-count example when comparing polygon formulas.

Dodecagon checks to make

• Do not assume the regular-case angle values belong to every dodecagon.
• Do not confuse a twelve-sided polygon with a ten-sided or eight-sided figure when the sides are short and numerous.
• Do not forget that the side-count name comes first and the regularity information comes second.