In regular octagon ABCDEFGH, M and N are midpoints of line BC and line FG respectively. Compute [ABMO]/[ABCDEFGH]. ([ABCD] denotes the area of polygon ABCD.)
To make it clearer, we can see that the midpoints of the octagon and the vertices create 16 congruent triangles, thus ABMO consists of 3 congruent triangles and MCDEO consists of 5 of them, thus the answer is 3/5.
