To find the value of a given exterior angle of a regular polygon, simply divide 360 by the number of sides or angles that the polygon has. For example, an eight-sided regular polygon, an octagon, has exterior angles that are 45 degrees each, because 360/8 = 45.
If each interior angle is 8 times the degree measure of each exterior angle how many sides does the polygon have. Now 8+1 = 9. Divide 180 by 9 to get 20.
The area of the mat = total area added minus the original area of the water color painting. length of the mat is:L = 20 in + 1 in + 1 in because 1 in is added to each sideL = 22 inwidth of the mat is:w = 9 in + 1 in + 1inw = 11 in Area mat = (22 in x 11 in) - ( 20 in x 9 in) area mat = 62 sq in is the area of the mat
