An undecagon, or figure with 11 sides. has an interior angle of 147o
Each interior angle will measure 162 degrees
Providing that it is a regular octagon then each interior angle will measure 135 degrees
The measure of each interior angle of a fifteen sided regular polygon, a pendedecagon, is 156o.
It is: 180-exterior angle = interior angle because there are 180 degrees on a straight line
A regular trapezoid (!) is a square. And each interior angle of a square is 90 degrees.
135 Each interior angle of a regular octagon measures 135 degrees.
Each interior angle of a regular 8 sided octagon measures 135 degrees
Each interior angle of a regular 9 sided nonagon measures 140 degrees
Each interior angle measures 140 degrees