What is an eight-sided polygon called?

An eight-sided polygon is called an octagon.

An octagon has 8 sides, 8 vertices, and therefore also 8 angles.

To form a triangle, at least three non-collinear points are required. In an octagon, the eight vertices are the defining points of the polygon.

In general, a polygon with n sides is referred to as an n-sided polygon, where the number of sides equals the number of vertices and the number of angles.

Regular vs. Irregular Polygons

• Regular polygon: all sides are equal and all interior angles are equal (high symmetry).
• Irregular polygon: sides and/or angles are not all equal (less symmetry).

For a regular polygon with n sides:

Interior angle of each vertex: π(n − 2)/n

Exterior angle of each vertex: 2π/n

If both sides and angles are equal, the polygon is classified as a regular polygon.