54 Diagonals.
* * * * *
A polygon with n sides has 1/2*n*(n-3) diagonals. So a decagon would have 1/2*10*7 = 35 diagonals. How the Community answer got 54 is anybody's guess!
There are 35 diagonals in a 10 sided decagon
In a 2d diamond there are 2 diagonals.
A tetra-decagon is a 14 sided polygon having 77 diagonals
35.
35
35
A decagon has 10 sides and 35 diagonals
35 diagonals
Ten.
35 diagonals
Decogon * * * * * A decagon, actually.
Yes.