Angle Bisector
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Definition of 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 an angle bisector at times. For example, the angle bisectors of polygons are line segments.
Examples of Angle Bisector

In the example shown, OA is the angle bisector. It divides 60^{0} into two equal parts (i.e. two 30^{0}'s).
Video Examples: Angle Bisector  Geometry Help
Solved Example on Angle Bisector
Ques: In the given figure, is the angle bisector of ∠AOB and is the angle bisector of ∠COB. If m∠AOC = 3y  4 and m∠COD = 28, then find the value of y.
Choices:
A. 56^{0}B. 28^{0}
C. 20^{0}
D. 112^{0}
Correct Answer: C
Solution:

Step 1: m∠COD = 28, so m∠BOC = 56, because is an angle bisector of ∠COB.
Step 2: m∠BOC = 56 implies that m∠AOC = 56, because bisects ∠AOB.
Step 3: So, 3y  4 = 56 gives y = 20^{0}.
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