Octadecagon

A octadecagon is a polygon with 18 sides and 18 vertices.

Regular Octadecagon

A regular octadecagon is a polygon with 18 equal sides and angles.

Angles of the Octadecagon

The sum of interior angles of an octadecagon = (18 − 2) · 180° = 2,880°

The value of an interior angle of a regular octadecagon is: 2,880º : 18 = 160º

The central angle of a regular octadecagon measures: 360º : 18 = 20º

Diagonals of the Octadecagon

The number of diagonals in a regular octadecagon = 18 · (18 − 3) : 2 = 135

Perimeter of a Regular Octadecagon

Perimeter = 18 · l

Area of a Regular Octadecagon

Area of a Regular Pentagon Formula