Interior of an Angle
From Latin: interior - "inner"
Definition: The area between the rays that make up an angle, and extending away from the vertex to infinity.
Try this Drag an orange dot. The point K will indicate if it is within the interior of angle ABC (shown in yellow). Or, drag the point K.

The interior of an angle is the area between the two rays that define it, shown in yellow above. Even if the angle is made up of line segments and so have a finite length, the interior extends beyond them forever. In the figure above, drag the point K and notice that it is in the interior of ABC even beyond the ends of the line segments BA and BC forming the angle.

NOTE: Do not confuse this with the interior angles of triangles and other polygons.
While you are here..

... I have a small favor to ask. Over the years we have used advertising to support the site so it can remain free for everyone. However, advertising revenue is falling and I have always hated the ads. So, would you go to Patreon and become a patron of the site? When we reach the goal I will remove all advertising from the site.

It only takes a minute and any amount would be greatly appreciated. Thank you for considering it!   – John Page

Become a patron of the site at

Other angle topics


Angle Types

Angle relationships