20 diagonals
Octagons have no perpendicular lines.
There are 64 sides in eight octagons.
Vertices don't have octagons but octagons have vertices. Assuming this is what you meant, 8.
alot
64.
It has 1,345,890 diagonals
24 sides
A undecagon has 44 diagonals. A dodecagon has 54 diagonals. An octagon has 20 diagonals. A heptagon has 14 diagonals.
An octagon has eight sides, so three octagons altogether have 8 * 3 = 24 sides.
3
24 diagonals
2 diagonals