Included angle definition - Math Open Reference

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Included angle

From Latin: includere "to shut in, enclose"

Definition: The angle made by two lines with a common vertex

Included angle - the angle between two given lines that meet at a point

When two lines meet at a common point (vertex) the angle between them is called the included angle. The two lines define the angle. So for example in the figure above we could refer to the angle ∠ABC as the "included angle of

and

".

Or we could refer to "

and

and their included angle".

Related angle topics

General

Angle Types

Angle relationships