1. Warm Up 11.03.11 Week 3 Tell whether it is possible to draw each triangle: 1) right isosceles triangle 2) scalene equiangular triangle 3) right scalene triangle

2. Geometry 4.2 Day 2 I will identify congruent figures and corresponding parts. Congruent Statement Ex 1 A sentence or math expression expressing that two shapes are congruent. ∠ A ≅ ∠ B because they are equal to each other. 38 ⁰ B A C E F Ex 2 ∠ E ≅ ∠ F because they are vertical angles. Congruent StatementShape

3. Ex 1 Prove both angles are congruent: 62º N M P R Q ≅, ≅ ≅,. 2) ∠ P ≅ ∠ N 3) ∠ NQM ≅ ∠ PQR 4) ∠ R ≅ ∠ M because they are both equal: 62º. because they are vertical angles. because of the third angle theorem. 1) 5) ∆PQ R ≅ ∆NQ M because of the definition of congruent triangles.

4. Theorem 4.4 Properties of Congruent Triangles REFLEXIVE: Every triangle is congruent to itself. SYMMETRIC: If ∆ ABC ≅ ∆ DEF, then ∆ DEF ≅ ∆ ABC. TRANSITIVE: if ∆ ABC ≅ ∆ DEF and ∆ DEF ≅ ∆ JKL, then ∆ ABC ≅ ∆ JKL. A B C D E F J K L

5. A B C D E F 40º 80º 5mº Given: ∠ A ≅ ∠ D and ∠ B ≅ ∠ E, find the value of m. 1) ∠ B ≅ ∠ E so m ∠ B = m ∠ E. 2) m ∠ B = 80º because ∠ B is equal to ∠ E. 3) m ∠ C = 60º because of T4.1. 4) 60º = 5mº because of T4.3. 5) 12 = m

6. Do: 1 Assignment: Textbook Page 207, 24 - 32 all. What is the m∠R and the value of x? 72º N M P R Q 42º 4xº