1. Warm Up 11.16.11 Week 5 How many acute angles for each type of triangle? 1) Acute 2) Right 3) equilateral 4) obtuse 3 2 3 2

2. Geometry 4.6 Day 1 I will use properties of isosceles triangles. Ex 1 IsoscelesA triangle with two congruent sides. Vertex Angle Leg Base Base Angles

3. Ex 2 Base Angles Theorem If two sides of a triangle are congruent, then the angles opposite them are congruent. Theorem 4.6 A B C If ≅, then ∠ B ≅ ∠ C.

4. A B C Ex 2 Base Angles Theorem Converse If two angles of a triangle are congruent, then the sides opposite them are congruent. Theorem 4.7 then ≅. If ∠ B ≅ ∠ C,

5. Ex 2 ∠ B ≅ ∠ C Prove: In ∆ABC, ≅ Given: A B C D 2) ∠ CAD ≅ ∠ BAD Definition of bisector Bisects ∆CAB 1) 3) ≅ 4) ∆CAD ≅ ∆BAD SAS Reflexive Property 5) ∠ B ≅ ∠ C CPCSC

6. Ex 3 xº yº 47º Solve for x and y: y = 47x = 180 - 47 - 47 x = 86

7. Do: 1 Assignment: Textbook Page 239, 8 - 16 all. Prove: ≅ Q S R P T