Triangle Congruence Proofs – Vocab Reference Sheet
Vocab Word
Definition
Midpoint
The point that divides a
segment into two
congruent segments
Definition of Midpoint
Segment
Bisector
A point, ray, line, line
segment, or plane that
intersects a segment at
its midpoint
Definition of Segment
Bisector
Angle Bisector
A ray that divides an
angle into two angles
that are congruent
Picture
Reason
Definition of Angle Bisector
Perpendicular
Bisector
A line that is
perpendicular to a
segment at its midpoint
Definition of Perpendicular
Bisector
Perpendicular
Lines
Two lines that intersect
to form a right angle
Definition of Perpendicular
Lines
Parallel Lines
Are two lines in the
same plane that never
meet.
Corresponding Angles are ≅
Alt. Ext. Angles are ≅
Alt. Int. Angles are ≅
Triangle Congruence Proofs – Vocab Reference Sheet
Vertical
Angles
Angles opposite each
other where two lines
cross.
Definition of
Vertical Angles
2 Right Angles
An angle that has a
measure of 90
All right angles are ≅
Reflexive
Property
States that an angle, line
segment, or shape is
always congruent to
itself.
Reflexive property of
Congruence
Symmetric
Property
If AB ≅ CD, then CD ≅
AB
Symmetric property of
Congruence
Transitive
Property
If AB ≅ BC and
BC ≅ CD,
then AB ≅ CD
Transitive property of
Congruence
Substitution
Property
If x = y, then x can be
substituted in for y in
any equation, and y can
be substituted for x in
any equation.
Substitution Property of
Congruence