No, it's not.
A regular hexagon.
6
A regular decagon, or 10-sided polygon, has interior angles of 144
180 sides!
No. To elaborate, the smallest regular polygon, an equilateral triangle, has 60 degree interior angles. The next larger one, a square, has 90 degree interior angles. In fact, for any regular polygon, the interior angles measure 180*(n-2)/n degrees, where n is the number of sides. No polygon has less than 3 sides. Thus, no regular polygon can have interior angles less than 60 degrees.
No.
Most certainly. That regular polygon is an equilateral triangle.
A regular polygon having an interior angle measure of 168o has 30 sides and is called a triacontagon.
Only if the polygon is "regular".
Only when it is a regular polygon that all interior angles are of equal measure
If the measure of an interior angle of a regular polygon is 140o, the polygon is a nonagon (sometimes called an ennagon) having 9 sides.
The measure of each interior angle of a fifteen sided regular polygon, a pendedecagon, is 156o.
A 13 sided regular polygon
The interior angle of an octdecagon, an 18 sided regular polygon, is 160o.
No.
A regular polygon with 4 sides is a square. The measure of any interior angle of a square is 90 degrees.
Only if the polygon is a "regular" one.