An angle bisector is a line or ray that divides an angle into two equal parts. It starts at the vertex of the angle and extends outward, ensuring that the two resulting angles have the same measure. This concept is important in geometry and is often used in various constructions and proofs. In a triangle, the angle bisector has special properties. For example, the Angle Bisector Theorem states that the ratio of the lengths of the two sides adjacent to the angle is equal to the ratio of the lengths of the segments created on the opposite side by the angle bisector.