Congruent triangles

Side-Side-Side (SSS) postulate

Two triangles are congruent if they have 3 pairs of congruent, corresponding sides.

Side-Angle-Side Postulate (SAS)

Two triangles are congruent if they have 2 pairs of congruent, corresponding sides and their included angle is congruent. 

Angle-Side-Angle Postulate (ASA)

Two triangles are congruent if they have 2 pairs of congruent, corresponding angles and their included side is congruent.

Angle-Angle-Side Postulate (AAS)

Two triangles are congruent if they have 2 pairs of congruent, corresponding angles and their non-included side is congruent.

Hypotenuse-Leg (Hy-Leg) Theorem

If two right triangles have their hypotenuses congruent and a pair of corresponding legs congruent, then the triangles are congruent. 

Angle Bisector

A line segment drawn in a triangle is an angle bisector iff it bisects an angle of a triangle.

Altitude

A line segment drawn in a triangle is an altitude iff it is drawn from a vertex perpendicular to the opposite side. 

Median

A line segment drawn in a triangle is a median iff it connects a vertex to the midpoint of the opposite side. 

If a line _______ the vertex angle of an isosceles triangle, then the line is also the perpendicular bisector of the base. 

Bisects

If two sides of a triangle are congruent, then the angles opposite those sides are _________.

Congruent

If two angles of a triangle are congruent, then the sides opposite those angles are _________.

Congruent

If two lines intersect to form congruent adjacent angles, then the lines are _____________.

Perpendicular

If two lines intersect to form congruent adjacent angles, then the angles are _____ angles. 

Right

If a point lies on the perpendicular bisector of a segment, then the point is ___________ from the endpoints of the segment.

Equidistant

If a point is equidistant from the endpoints of a segment, then the point lies on the _____________ ________ of the segment.

Perpendicular bisector