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Dodecagon
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Geometry Hub / Polygons / Dodecagon
05.18 • Polygons

Dodecagon

Use side count and regular-angle structure together to read dodecagon as a twelve-sided polygon with strong symmetry.

Interactive diagram Live labels and measurements Worked examples PNG graph downloads
Dodecagon
Interactive diagram

Dodecagon Diagram

Track the twelve sides and compare the figure's side-count identity with the regular case's one-hundred-fifty-degree interior angles.

Use the movable diagram to see what defines dodecagon, how the labels relate to the figure, and what stays true as the board changes.

Definition: A dodecagon is a polygon with twelve sides.
Detailed definition

Understanding Dodecagon

Dodecagon is a polygon with twelve sides. A dodecagon is a polygon with twelve sides. The name stays the same whether the polygon is regular or irregular, but the regular case adds especially clear angle and symmetry properties.

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.

Key facts

Important ideas to remember

  • 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 it is used

Where dodecagon shows up

  • 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.
Common mistakes

What to watch out for

  • 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.
Worked examples

Dodecagon examples

Use these worked examples to see the idea in a clean diagram first, then in the kind of reasoning students usually need for classwork, homework, or test practice.

Example 1

Example 1: Naming a dodecagon from its side count

Count the sides and vertices carefully so the polygon name comes from the correct total.

  • Start at one vertex and count around the boundary once.
  • Match the count to the standard polygon name.
  • Check that the shape closes after the final side.

Result: The polygon is named accurately because the side count and vocabulary agree.

Example 2

Example 2: Connecting dodecagon to its regular form

Use the same side count to discuss the regular version of the polygon without changing the name itself.

  • Keep the side count fixed.
  • Notice how equal sides and equal angles change the look of the figure.
  • Separate the naming rule from the regularity rule.

Result: The student can name the polygon first and then discuss whether it is regular or irregular.

For

Why this page helps

This page helps because dodecagon introduces a larger polygon that still has highly manageable regular-case values. It is a good bridge from named polygons to more general polygon formulas.

Do

What you can do here

  • Compare the twelve-sided boundary with the regular dodecagon's clean angle pattern.
  • See how a large regular polygon begins to resemble a circle without becoming one.
  • Download a clear dodecagon diagram for side-count, angle, or symmetry review.
Learning outcome

What this page helps you do

These takeaways are meant to help you recognize the idea faster, read diagrams more accurately, and use the topic with more confidence in real problems.

1

Dodecagon

Name larger polygons more confidently from side count.

2

Dodecagon

Use regular dodecagon angles and diagonal counts with better control.

3

Dodecagon

Bridge named polygons and general polygon formulas more smoothly.

05

Back to Polygons

Return to the category page to open another concept in polygons.

ST

Geometry Construction Studio

Use a dedicated geometry drawing board for points, segments, rays, lines, angles, circles, triangles, rectangles, pencil sketches, and virtual measuring tools.

05.17

Previous: Decagon

A decagon is a polygon with ten sides.

05.19

Next: n-gon

An n-gon is a polygon described by a general number of sides n.