Angle Bisector
Definition of An Angle Bisector
- Angle bisector is a ray that divides an angle into two equal parts.
More about Angle Bisector
- Angle bisector is also called the internal angle bisector.
- Angle bisectors of a triangle intersect at a point called incenter of the triangle.
- A line or a line segment can also be angle bisectors at times. For example, the angle bisectors of polygons are line segments.
Examples of An Angle Bisector
In the example shown, OA is the angle bisector. It divides 60° into two equal parts, (two 30°'s).
Solved Example on Angle Bisector
In the given figure,
is the angle bisector of
and
is the angle bisector of
. If
and 
, then find the value of y.
Choices:
A. 56°
B. 28°
C. 20°
D. 112°
Correct Answer: C
Solution:
Step 1: , so
, because is an angle bisector of .
Step 2: implies that 
, because bisects .
Step 3: So, 3y - 4 = 56 gives y = 20°.
Related Terms for Angle Bisector
Additional links for Angle Bisector
