Download Legs

Module 15: Lesson 2
Isosceles 7 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.
Vertex
Angle
Leg
Leg
Base
Base
Angles
Legs: The sides that are
congruent in length.
Vertex Angle: Angle
formed by the legs.
Base: The side opposite
the vertex angle.
Base Angles: The
angles opposite the
legs.
The Isosceles Triangle Theorem
When the legs are congruent then the base angles are congruent.
A
Given: BA  CA,
Statement
B
C
If AB  AC , then B  C
BA  CA
A  A
CA  BA
ΔBAC
 ΔCAB
B  C
Prove: B  C
Reason
The Converse of the Isosceles Triangle Theorem
When the base angles are congruent then the legs are congruent.
A
B
C
If B  C , then AB  AC
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.
Homework pages 745-750 #’s 1-20 (all)