60 sides
180-174 = 6
360/6 = 60
Providing that it is a regular 28 sided polgon then each interior angle will measure: 1670 8' 34.29''
180
It wil be a regular 18 sided polgon
Each interior angle will measure 162 degrees
720 degrees
360/18 ie 20 sides
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
144
120°
135 Each interior angle of a regular octagon measures 135 degrees.
Each interior angle of a regular 9 sided nonagon measures 140 degrees