Aim:

1. Aim: K Given: C A B Prove: What theorems apply to isosceles and equilateral triangles? Do Now: Given Given Def. angle bisector Reflexive Postulate S.A.S. Postulate C.P.C.T.C. Geometry Lesson: Isosceles and Equilateral Triangle Theorems

2. Isosceles Triangle Theorem: T E P ) Z ) ) ) G ) ) D Q V M ) ) Theorem #8: Base angles of an isosceles triangle are congruent. Isosceles triangles Corollary #8-1: The bisector of the vertex angle of an isosceles triangle bisects the base. Corollary #8-2: x The bisector of the vertex angle of an isosceles triangle is perpendicular to the base. In other words:The median, altitude and angle bisector from the vertex of an isosceles triangle are all the same segment. Geometry Lesson: Isosceles and Equilateral Triangle Theorems

3. B B B Or Or ) ) ) ) ) ) A C A C A C B ) ) ) C Equilateral Triangles Corollary #8-3: Every equilateral triangle is equiangular. Geometry Lesson: Isosceles and Equilateral Triangle Theorems

4. L Q K D F T Ex: Isosceles Triangles If the following pairs of segments are congruent, which angles are congruent. Geometry Lesson: Isosceles and Equilateral Triangle Theorems

5. V Given: A T K R M Prove: Ex: Proof w/Isosceles Triangle Given Given Def. Of midpoint Given A.S.A. Postulate C.P.C.T.C Geometry Lesson: Isosceles and Equilateral Triangle Theorems

6. 1) Given: Prove: D 2) Given: T M R Prove: V y x A 3) Given: G D H T Q N Prove: L E P Proofs w/Isosceles Triangles Geometry Lesson: Isosceles and Equilateral Triangle Theorems

7. Algebra w/Isosceles Triangles Geometry Lesson: Isosceles and Equilateral Triangle Theorems