A regular decagon is a decagon with all sides equal in length and all the angles equal in measure. In a regular decagon, the interior angles add up to 1440 degrees, and the exterior angles add up to 360 degrees. An irregular decagon is the type of decagon with unequal sides and angles. Here is what these decagons look like: A decagon is a 10 sided polygon with interior angles that add to 1440 degrees. Regular decagons have sides of equal length and interior angles of 144 degrees. An pentadecagon is a 15 sided polygon with interior angles that add to 2340 degrees. An icosagon is a 20 sided polygon with interior angles that add to 3240 degrees.
A regular decagon, or 10-sided polygon, has interior angles of 144 The exterior angles of any polygon always add up to 360 degrees A decagon is a 10 sided polygon A decagon is a 10 sided polygon A regular dodecagon is a figure with sides of the same length and internal angles of the same size. It has twelve lines of reflective symmetry and rotational symmetry of order 12.