What is exterior angle? How to use in English

Discover the meaning of exterior angle in English, its pronunciation, and how to use it correctly in real-life situations. See examples and easy memorization tips.

Definition & pronunciation of exterior angle

exterior anglenoun
góc ngoài
/ɪkˌstɪəriər ˈæŋɡl//ɪkˌstɪriər ˈæŋɡl/

Where does the word exterior angle come from?

The term "exterior angle" in geometry refers to the angle formed on the outside of a polygon by extending one of its sides. Essentially, it is the angle formed by a line (an extended side) and another line meeting at a vertex outside the polygon. This concept is important in understanding the properties and characteristics of polygons, since the exterior angles, along with the interior angles, help to define their shape and behavior. In fact, the sum of all the interior and exterior angles in a polygon is always equal to 360 degrees. The concept of exterior angles originated in the ancient Greek mathematics and architecture, where it was used to design buildings and structures with precise angles and measurements. Today, it is a fundamental element of geometry, algebra, and trigonometry, with applications in various fields like engineering, computer graphics, and surveying.

Example of vocabulary exterior anglenamespace

In a triangle, the exterior angle opposite the vertex of C is formed by drawing a line perpendicular to the side containing C and extending it beyond the vertex. This angle is designated as ☲C.
The exterior angle of a regular polygon is the angle formed outside the polygon by joining the endpoints of two adjacent sides with a line.
To calculate the measure of an exterior angle, find the sum of the interior angles and subtract it from 180 degrees.
The exterior angle of a cyclic quadrilateral is the supplement of the interior opposite angle.
To construct the exterior angle of a triangle, bisect one of the sides and extend the bisector until it meets the side on the other side of the vertex. The exterior angle is formed by joining the endpoint of this extended line to the adjacent vertex.