The measure of the entire interior of a regular decagon is 1440 degrees. 1440 divided by 10 equals 135 degrees. Therefore, 135 degrees is your final answer.
If it had n sides, the sum of its interior angles would have been (n-2)*180 degrees. That would require (n-2)*180 = 1140 This requires that 180 divides into 1140. It does not so there is no such polygon.
a right angle equals 90 degrees.
A 13 sided polygon also called a triskaidecagon or tridecaogn has a total 1980 degrees for its interior angles.
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.
an equilateral triangle, or equiangular triangle
If it is a regular polygon then it will have 360/12 equals 30 sides
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
With any regular polygon it is 180 minus interior angle times number of sides equals 360 degrees
Sum of interior angles = (n-2)*180 degrees = 1080 deg So (n-2) = 1080/180 = 6 => n = 8. The polygon is, therefore, an octagon. However, there is no reason to assume that the interior angles of this polygon are all the same - they could all be different with the only constraint being their sum. IF, and that is a big if, the polygon were regular, then all its angles would be equal and each interior angle = 1080/8 = 135 degrees.