1. 4.6 Isosceles and Equilateral Triangles

2. Legs of an Isosceles Triangle
The two _____________________________ are called ___________ of an isosceles triangle.
The ___________ with the sides that are _________________ is called the vertex angle.
The ____________ of the triangle ________________ the vertex angle is called the base. The _____________ formed by the base and _______ ___________________ are called the base angles.
Vertex Angle
Base Angles

3. Isosceles Triangle Theorem
If two __________________ of a triangle are ________________,
then the _________ opposite those sides are
_____________________.
Converse Isosceles Triangle Theorem
If two ________________ of a triangle are congruent, then
the sides ____________________ those angles are
congruent.

4. Example 1 a) Name two unmarked congruent angles.
b) Name two unmarked congruent segments.

5. Example 1 Continued
c) Which statement correctly names two congruent angles?
a) ÐPMJ
b) ÐJKM
c) ÐJKP 
d) ÐPLK

6. Equilateral Triangle (4.3)
A triangle is _____________________ only if it is
_________________________.
Equilateral Triangle (4.4)
Each _________ of an equilateral triangle measures
________.

7. Example 2
a) Find mÐR
b) Find PR.

8. Example 3
You can use the properties of equilateral triangles and algebra to find missing values.
Find the value of each variable.

9. Summary

10. Summary

11. Summary