1. Module 15: Lesson 2 Isosceles & Equilateral Triangles
An isosceles triangle is a triangle with at least 2 sides congruent or the same length.
An equilateral triangle is a triangle all 3 sides congruent or the same length.

2. Legs: The sides that are congruent in length.
Vertex Angle
Vertex Angle: Angle formed by the legs.
Leg
Leg
Base: The side opposite the vertex angle.
Base Angles: The angles opposite the legs.
Base
Base Angles

3. The Isosceles Triangle Theorem
When the legs are congruent then the base angles are congruent. A
Reason
Statement B C
ΔBAC
ΔCAB

4. The Converse of the Isosceles Triangle Theorem
When the base angles are congruent then the legs are congruent. A B C

5. Equilateral Triangle: All 3 sides are the same length.
Equiangular Triangle: All 3 interior angles are the same measure.
The Equilateral Triangle Theorem
All equilateral triangles are equiangular.
The Converse of the Equilateral Triangle Theorem
All equiangular triangles are equilateral.

6. Homework pages 745-750 #’s 1-20 (all)