Supplementary pair of angles at each vertex of a polygon
"Interior angle" redirects here. For interior angles on the same side of the transversal, see Transversal line.
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The corresponding internal (teal) and external (magenta) angles of a polygon are supplementary (sum to a half turn). The external angles of a non-self-intersecting closed polygon always sum to a full turn.
Types of angles
2D angles
Right
Interior
Exterior
Spherical
2D angle pairs
Adjacent
Vertical
Complementary
Supplementary
Transversal
3D angles
Dihedral
Solid
v
t
e
Internal and external angles
In geometry, an angle of a polygon is formed by two adjacent sides. For a simple (non-self-intersecting) polygon, regardless of whether it is convex or non-convex, this angle is called an internal angle (or interior angle) if a point within the angle is in the interior of the polygon. A polygon has exactly one internal angle per vertex.
If every internal angle of a simple polygon is less than a straight angle (π radians or 180°), then the polygon is called convex.
In contrast, an external angle (also called a turning angle or exterior angle) is an angle formed by one side of a simple polygon and a line extended from an adjacent side.[1]: pp. 261–264
^Posamentier, Alfred S., and Lehmann, Ingmar. The Secrets of Triangles, Prometheus Books, 2012.
and 29 Related for: Internal and external angles information
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