Since the sum of the n central angles (where n is also the number of sides) of a regular polygon is 360 degrees, then our polygon has 9 sides (360/40) and it is called a nonagon.
square
straight angle.
An acute angle
Obtuse angle
A 90-degree angle is commonly called a right angle.
square
The interior angles of a triangle add up to 180 degrees. Every time you add an angle, you add another 180 degrees (mark a point on a side of a polygon and call it a straight angle; that is not exactly a proof but it makes it reasonable that it is true). So the total is 180 times 2 less than the number of sides.
An acute angle
Obtuse angle
straight angle.
A bigger than 180 degrees angle
A 90-degree angle is commonly called a right angle.
revolution angle
an obtuse angle
An obtuse angle
It is an obtuse angle.
A right angle is a 90 degrees angle