This document discusses congruence and properties of congruent triangles. It defines congruence as two figures having the same size and shape, with corresponding angles and sides being congruent. If two triangles are congruent, corresponding angles and sides are congruent. The Third Angle Theorem states that if two angles of one triangle are congruent to two angles of another, the third angles are also congruent. Properties of congruent triangles include: reflexive, symmetric, and transitive properties. Examples are provided to illustrate these concepts.

1. 4.2 Congruence and Triangles Objectives: - Identify congruent figures and corresponding parts - Prove that 2 triangles are congruent

2. Congruence Two geometric figures are congruent if they have exactly the same size and shape. When two figures are congruent, there is a correspondence between their angles and sides such that corresponding angles are congruent and corresponding sides are congruent.

3. Congruence If QRS is congruent to ABC, which angles are congruent? Which sides are congruent? It is important to list the corresponding angles in the right order. SQR is congruent to CAB, NOT SRQ is congruent to ABC A B C Q R S

4. Turn to page 203 And do Example 2 together

5. Third Angles Theorem If 2 angles of one triangle are congruent to 2 angles of another triangle, then the third angles are also congruent.

6. Now do Example 3 P. 203 And Example 4 on 204 And example 5 on 205

7. Properties of Congruent Triangles Reflexive Property of Congruent Triangles Every triangle is congruent to itself Symmetric Property of Congruent Triangles If ∆ ABC ~= ∆ DEF, then ∆ DEF ~= ∆ ABC Transitive Property of Congruent Triangles If ∆ ABC ~= ∆ DEF and ∆ DEF ~= ∆ JKL then ∆ ABC ~= ∆ JKL

8. Do p. 205 2-9, 23, 33 Homework: worksheets Quiz tomorrow