A decagon is a 10-sided polygon. The formula for number of diagonals is $$\frac{n(n-3)}{2}$$Â
Substituting n as 10 we get, $$\frac{10(7)}{2} = 35$$Â
So there are 35 diagonals in a decagon.
Hence, option D is the correct answer.
Create a FREE account and get: