60
1260
140
An interior angle of a regular octagon is 45 degrees. The exterior angles measure 315 degrees.
The measure of the exterior angle of a convex octagon is indeterminate.
135
140
Any value between 0 and 360 degrees (excluding 180 degrees).
Providing that it is a regular octagon each interior angle measures 135 degrees
Any measure between 0 and 360 degrees (except 180 degrees).
40 degrees
140 degrees.
Providing that it is a regular nonagon then each exterior angle measures 40 degrees and each interior angle measures 140 degrees