1. 4-6 Isosceles & Equilateral Triangles
Objectives:
The student should be able to:
1. Use properties of Isosceles triangles.
2. Use properties of Equilateral triangles.

2. Properties of Isosceles Triangles
Isosceles triangle - a triangle with tow congruent sides called legs.
Vertex angle - The angles formed by congruent sides.
Base angles – the other two angles (that are not the vertex angle, opposite the legs) of an isosceles triangle.
Isosceles triangle theorem – If two sides of a triangle are congruent, then the angles opposite those sides are congruent. In ΔJHL, so
Also, If two angles of a triangle are congruent, then the sides opposite those sides are congruent. In ΔJHL, so

3. Properties of Equilateral Triangles
A triangle is equilateral if and only if it is equiangular.
Each angle of an equilateral triangle measures 60°.

4. Example 1:
Find the measure of each side.
Example 2:
Find the measure of each side.

5. Example 3:
Find the measure of each each angle.
Example 4:
Find the measure of each each angle.

6. Example 5:
Find the measure of each each angle.
Example 6:
Find the measure of each each angle.

7. Example 7:
Find the measure of each side and each angle.