Definition of a Bisector
A ray which divides an angle into two congruent parts
Angle Bisector Theorem
If ray BF is an angle bisector, then m(a)CBF = m(a)FBA = 1/2m(a) CBA
A plane, point, line, ray or segment which divides a segment into two congruent parts. One of the segments formed by a segment bisector is equal in length to half the length of the original segment.