|Interior angle||150°||Like any regular polygon, to find the interior angle we use the formula (180n–360)/n . For a dodecagon, n=12. See Interior Angles of a Polygon|
|Exterior Angle||30°||To find the exterior angle of a regular dodecagon, we use the fact that the exterior angle forms a linear pair with the interior angle, so in general it is given by the formula 180-interior angle. See Exterior Angles of a Polygon|
|Where S is the length of a side. To find the exact area of a dodecagon or any polygon, using various methods, see Area of a Regular Polygon and Area of an Irregular Polygon|
|Number of diagonals||54||The number of distinct diagonals possible from all vertices. (In general ½n(n–3) ). In the figure above, click on "show diagonals" to see them. See Diagonals of a Polygon|
|Number of triangles||10||The number of triangles created by drawing the diagonals from a given vertex. (In general n–2). In the figure above, click on "show triangles" to see them. See Triangles of a Polygon|
|Sum of interior angles||1800°||In general 180(n–2) degrees . See Interior Angles of a Polygon|
Dodecagons are not seen much in everyday life. However, in Australia, there are coins in the shape of a dodecagon.
Below is the 12-sided Australian 50 cent coin.