A triangle
A 13 sided polygon also called a triskaidecagon or tridecaogn has a total 1980 degrees for its interior angles.
120
Im stuck on that too :/
2280 :S
The sum of the interior angles of any regular polygon of n sides is equal to 180(n - 2) degrees.
If the polygon has n sides, the sum of its interior angles is 180*(n-2) degrees.
It will have 8 sides and it is called a regular octagon.
It is a hexagon.
If it is a regular polygon with each interior angle of 120 degrees then it is an hexagon which will have 0.5((6^2)-3*6) equals 9 diagonals
A [regular] hexagon.
With any regular polygon it is 180 minus interior angle times number of sides equals 360 degrees