Polygon angle sums

Math

Definition

The sum of interior angles of a polygon depends on the number of sides. For any n-sided polygon, the interior angle sum is (n-2) × 180°. Each exterior angle and its adjacent interior angle sum to 180°.

Examples

  • Triangle: (3-2) × 180° = 180°
  • Pentagon: (5-2) × 180° = 540°
  • Each interior angle of a regular hexagon: 720°/6 = 120°
Key Fact

Interior angle sum = (n-2) × 180°; Exterior angle sum always = 360°

Related Terms

Regular polygons Triangles Area of polygons

Study This Concept

Practice polygon angle sums with free review games in these units:

Geometry Unit 6: Quadrilaterals and Polygons