Skip to main content
Glite Dictionary
exterior angle

exterior angle

5.5
An angle outside a shape with straight sides made by a side and the next side extended
  • noun
  • /ɪkˈstɪəriər ˈæŋɡəl/
  • Specialized
translation icon : ángulo exterior
  • In geometry, the exterior angle is equal to the sum of the two opposite interior angles.

Examples

  • The measure of an exterior angle at a vertex of a polygon is calculated by extending one of its sides.

  • Alternate exterior angles are also equal.

  • " What are vectors and exterior angles? " she thought.

    Fiction book (2001)

  • To find the exterior angle of a triangle, measure one of its interior angles and subtract that from 180 degrees.

Synonyms

external angle
vsexterior angle
  • Specialized
6.3

An angle outside a polygon that forms when one side is extended

has identical meaning but uses a different adjective form

Antonyms

interior angle
  • Specialized
1 3.9

The space inside a shape with straight sides where two sides meet

Surface Forms

exterior angle singular
exterior angles plural

Morphology

exterior + angle

The adjective 'exterior' means outside and 'angle' refers to the measure between lines, so a B1 learner who knows both words will readily infer that an 'exterior angle' is an angle located outside a shape. The formal geometric details (formed by a side and the extension of an adjacent side, equal to the supplement of the interior) are technical but do not obscure the transparently composed basic meaning, which is also cross-linguistically common.

Etymology

The term exterior angle comes from the picture of an angle on the 'outside' of a many-sided shape, made when one side and the continued next side meet. That's why an exterior angle and the 'inside' angle next to it make a straight line (180°), so the name means the angle you find outside the shape.