Concept of Angle Bisector

If a line or line segment divides an angle into two equal angles, then the line or line segment is called the angle bisector of the given angle.
OD is the angle bisector of ∠COA
QS is the angle bisector of ∠RQP

Properties of an Angle Bisector:

• An angle bisector divides an angle into two equal parts.
• Any point on the bisector of an angle is equidistant from the sides or arms of the angle.
• A triangle divides the opposite side into the ratio of the measures of the other two sides.

To Understand Angle Bisector:
1. Draw an angle of any measure on tracing paper.
2. Fold the paper so that both arms of the angle overlap each other.
3. Observe the fold:

• The fold divides the angle into two equal parts.
• This fold is called the angle bisector.

4. Mark points A and B on each arm of the angle:

• Keep equal distance from the vertex (common starting point of the angle).

5. Mark points C, P, and T on the bisector line (fold).
6. Measure the distance from each point (C, P, T) to both A and B.
7. Observe:

• The distances from each bisector point (C, P, T) to A and B are equal.