0
Wiki User
a triangle has 0 diagnols
8
2
None
35
44
A polygon with n sides has n*(n-3)/2 diagonals (not diagnols!).So, an octagon has 8*5/2 = 20 of them.
3
six
no
It is an octagon
Formula: 0.5*(n2-3n) where n is the number of sides