Lesson 4-2: Congruent Triangles

Lesson 4-2: Congruent Triangles Congruent Figures Congruent figures are two figures that have the same size and shape. IF two figures are congruent THEN they have the same size and shape. IF two figures have the same size and shape THEN they are congruent. Two figures have the same size and shape IFF they are congruent. Lesson 4-2: Congruent Triangles

Congruent Triangles - CPCTC Corresponding Parts of Congruent Triangles are Congruent Two triangles are congruent IFF their corresponding parts (angles and sides) are congruent. B C A Q R P = │ Vertices of the 2 triangles correspond in the same order as the triangles are named. ≡ A ↔ P; B ↔ Q; C ↔ R Corresponding sides and angles of the two congruent triangles: │ = ≡ Lesson 4-2: Congruent Triangles

Lesson 4-2: Congruent Triangles CPCTC ≡ DEF ABC WHICH ANGLES ARE CONGRUENT? Lesson 4-2: Congruent Triangles

Lesson 4-2: Congruent Triangles  Z B A C X Y Z =  Y  B  _____ ≡ │ ≡  X │  C  ______ = Note: ∆ ZYX ∆ABC  ______ ∆ABC  ∆XYZ Lesson 4-2: Congruent Triangles

Lesson 4-2: Congruent Triangles THIRD ANGLES THEOREM Lesson 4-2: Congruent Triangles

Lesson 4-2: Congruent Triangles Example………… When referring to congruent triangles (or polygons), we must name corresponding vertices in the same order. S U N R A Y R Y SUN  RAY A N U Also NUS  YAR Also USN  ARY S Lesson 4-2: Congruent Triangles

Lesson 4-2: Congruent Triangles Example ……… If these polygons are congruent, how do you name them ? P O U N M E A T S R Pentagon MONTA  Pentagon PERSU Pentagon ATNOM  Pentagon USREP Etc. Lesson 4-2: Congruent Triangles

Lesson 4-2: Congruent Triangles REFLEXIVE PROPERTY A AD is congruent to AD by the reflexive property. B C D Lesson 4-2: Congruent Triangles