Question 9180
First you need to find the sum of all the angles within a regular octagon.  To do this, draw an octagon (8 sides, like a stop sign!), select a vertex (any vertex will do!), and draw diagonals from that vertex to each other vertex in the octagon.  These diagonal will divide the octagon into 6 triangles (it's always 2 less than the number of sides in the figure being "diagonalized").  Each triangle has 180 degrees, which multiplied times 6 gives you 1080 degrees.  This 1080 degrees represents the sum of the 8 vertex angles of the octagon.  To find the size of each angle, divide 1080 by 8, or 135 degrees.


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