The sum of the interior angles of a regular polygon is 1080°.
a.) classify the polygon by the number of sides.

b.) what is the measure of one interior angle of the
polygon?

c.) what is the measure of one exterior angle of the
polygon?

Sum of Interior Angles = (Number of Sides -2) • 180 degrees

Number of Sides = (Sum of Interior Angles / 180 degrees) + 2

Number of Sides = (1,080 / 180) +2

Number of Sides = 6 + 2

Number of Sides = 8

a) It is an octagon

b) Each interior angle = 1,080 / 8 = 135 degrees

c) Each Exterior Angle = (360 degrees) ÷ (Number of Sides)

Each Exterior Angle = 360/8

Each Exterior Angle = 45 degrees

Source:
http://www.1728.org/polygon.htm