A polygon with 8 sides, also known as an octagon, has 20 diagonals.
Here's how to calculate that:
The general formula for the number of diagonals in a polygon with n sides is:
Number of diagonals = n(n-3) / 2
In this case, n = 8. Substituting this value into the formula, we get:
Number of diagonals = 8(8-3) / 2
Number of diagonals = 8(5) / 2
Number of diagonals = 40 / 2
Number of diagonals = 20
Therefore, an octagon has 20 diagonals.
