A regular icosagon is a 20-sided polygon with all angles and sides equal.
The formula for the sum of the interior angles of an n-sided polygon is:
S = (n - 2) × 180 degrees
Substituting n = 20, we get:
S = (20 - 2) × 180 degrees
S = 18 × 180 degrees
S = 3240 degrees
Therefore, the sum of the interior angles of a regular icosagon is 3240 degrees.