nonadecagon

A nonadecagon is a polygon with nineteen sides and nineteen vertices. In a regular nonadecagon, all sides are of equal length and all interior angles are equal. The sum of the interior angles of any nonadecagon, regardless of its regularity, is given by the formula (n-2) * 180 degrees, where n is the number of sides. For a nonadecagon, this sum is (19-2) * 180 = 17 * 180 = 3060 degrees.

The measure of each interior angle in a regular nonadecagon is 3060 degrees divided by 19, which is approximately 161.05 degrees. The exterior angle of a regular nonadecagon measures 360 degrees divided by 19, approximately 18.95 degrees. A nonadecagon can be constructed using a ruler and compass if and only if 19 is a Fermat prime or a product of distinct Fermat primes and a power of 2. Since 19 is a prime number but not a Fermat prime, a regular nonadecagon cannot be constructed with only a ruler and compass. The number 19 is not a Fermat prime, as Fermat primes are of the form 2^(2^n) + 1, and 19 does not fit this pattern.