Definition

1. Noun:
   • The supplement of an interior angle of a polygon: An exterior angle is the angle formed between one side of a polygon and the extension of an adjacent side. It is supplementary to the interior angle at that vertex, meaning the two angles add up to 180 degrees.

Usage Examples

• Noun:
  • To find the measure of an exterior angle of a regular hexagon, you can divide 360 by the number of sides.
  • In the diagram, the exterior angle is clearly marked outside the triangle.

Advanced Usage

• Sum of Exterior Angles: A key property is that the sum of the exterior angles of any convex polygon, one at each vertex, is always 360 degrees, regardless of the number of sides.
  • The theorem that the sum of the exterior angles is 360 degrees is fundamental in geometry.

Variants and Related Words

• External Angle: A less common but synonymous term for exterior angle.
• Interior Angle: The angle inside the polygon at a vertex, which is supplementary to the exterior angle.

Synonyms

• External angle

Related Concepts (Not Phrasal Verbs/Idioms)

• Supplementary Angles: Two angles whose measures sum to 180 degrees. An exterior angle and its corresponding interior angle are supplementary.
• Polygon: A closed plane figure bounded by straight lines, which has interior and exterior angles.

Noun

1. the supplement of an interior angle of a polygon