The answer will depend on the sum of what. The lengths of sides, the interior angles, the exterior angles, the lengths of diagonals, etc. Since you have not bothered to provide that information, I cannot provide a sensible answer.
The interior angles of an 11 sided polygon add up to 1620 degrees
360 degrees
The sum of the interior angles of a n-sided polygon is (n-2)*180 degrees. So for 13 sides, the sum is 11*180 = 1980 degrees.
(11-2)*180 = 1620 degrees
the 11 sided polygon is undecagon
The name of a 11 sided polygon is Hendecagon.
The interior angles of an 11 sided polygon add up to 1620 degrees
1620 degrees
360 degrees
The sum of the interior angles of a n-sided polygon is (n-2)*180 degrees. So for 13 sides, the sum is 11*180 = 1980 degrees.
Sum of exterior angles of any sided polygon is 360 so sum of exterior angle of 6 sided polygon (hexagon) is 360
(11-2)*180 = 1620 degrees
The name of a 21 sided polygon is Icosihenagon.
The name of a 16 sided polygon is Hexadecagon.
The sum of the interior angles of a four-sided polygon is 360 degrees.
the 11 sided polygon is undecagon
The sum of the exterior angles of any n-sided regular polygon, including a seven-sided polygon, is 360 degrees.