A 20 sided polygon has 170 diagonals
170
20 20
i think that it is 170, but im not positive...
252 diagonals
It has 495 diagonals.
There are 119 diagonals.
It has 54 diagonals
78
There are 275 diagonals in a 25 sided polygon
0.5*(152-45) = 90 diagonals
39*36/2 = 702 diagonals.
There are 44 diagonals in an 11 sided undecagon