1. Triangles and Isosceles Sum of angles and properties of isosceles

2. Triangle Sum Conjecture Conjecture – a generalization resulting from inductive reasoning Sum of angles of a triangle =180 Can you prove this without using a protractor

3. This is on page 201 Try and write a proof on why the angles add to 180

4. The proof StatementReason EC is a lineGiven AB is parallel to ECGiven 1+2+3=180def of a line 1=4AI 3=5AI 4+2+5=180Substitution

5. Properties of Angles Remember all the different angle properties 1.Vertical 2.Linear Pair 3.AI 4.AE 5.Corr 6.SSI

6. Isosceles Triangles 1.2 congruent sides - legs 2.2 congruent angles – formed by non congruent sides, base angles 3.Non Congruent side is called the base 4.Vertex – non congruent angle, formed by congruent sides

8. If legs are congruent then it is an isosceles triangle If base angles are congruent then it is an isosceles triangle

9. Examples Find the missing measures

10. Homework Pg 203 4-8 Pg 208 6-9 Honors pg 209 10