Term

Definition
If three sides of one triangle are congruent to three sides of another triangle, then the triangles are congruent. 


Term

Definition
If two sides and the included angle of one triangle are congruent to two sides and the included angle of another triangle, then the triangles are congruent. 


Term

Definition
If two angles and the included side of one triangle are congruent to two angles and the included side of another triangle, then the triangles are congruent. 


Term
Isosceles Triangle Theorem 

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


Term
Corollary 1 to the Isosceles Triangle Theorem (Don't call it this!) 

Definition
An equilateral triangle is also equiangular. 


Term
Corollary 2 to the Isosceles Triangle Theorem (Don't call it this!) 

Definition
An equilateral triangle has three 60 degree angles. 


Term
Corollary 3 to the Isosceles Triangle Theorem (Don't call it this!) 

Definition
The bisector of the vertex angle of an isosceles triangle is perpendicular to the base at its midpoint. 


Term
Converse of the Isosceles Triangle Theorem 

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


Term
Corollary to the Converse of the Isosceles Triangle Theorem (Don't call it this) 

Definition
An equiangular triangle is also equilateral. 


Term

Definition
If two angles and a nonincluded side of one triangle are congruent to two angles and a nonincluded side of another triangle, then the triangles are congruent. 


Term

Definition
If the hypotenuse and a leg of one right triangle are congruent to the hypotenuse and a leg of another right triangle, then the triangles are congruent. 


Term
Theorem 4.5 (don't call it this) 

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


Term
Theorem 4.6 (don't call it this) 

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


Term
Theorem 4.7 (don't call it this) 

Definition
If a point lies on the bisector of an angle, then the point is equidistant from the sides of the angle. 


Term
Theorem 4.8 (don't call it this) 

Definition
If a point is equidistant from the sides of an angle, then the point lies on the bisector of the angle. 


Term
Definition of a line perpendicular to a plane 

Definition
If a line and a plane intersect and the line is perpendicular to all lines in the plane that pass through the point of intersection. 


Term

Definition
A segment from the vertex to the midpoint of the opposite side. 


Term
Definition of an Altitude 

Definition
The perpendicular segment from a vertex to the line that contains the opposite side. 


Term
Definition of a perpendicular bisector 

Definition
A line (or segment or ray) that is perpendicular to the segment at its midpoint. 

