Isosceles Triangles

1. Properties of Isosceles
Triangles
Objectives:
Discover a relationship
between the base angles of an
isosceles triangle.

2. Isosceles Triangle – at least
two sides have the same
length

3. equilateral triangle:
isosceles triangle with all
three sides are congruent

4. Parts of Isosceles Triangle:
vertex angle –
between two @ sides

5. Parts of Isosceles Triangle:
base angles – angles
opposite @ sides

6. Parts of Isosceles Triangle:
base – side opposite
vertex

7. Name each part of the
isosceles triangle below.

8. Name each part of the
isosceles triangle below.

9. Name each part of the
isosceles triangle below.

10. Isosceles Triangle Theorem
If a triangle is isosceles, then
_______________________.base angles are congruent

11. Converse of Isosceles
Triangle:
If a triangle has two congruent
angles, it is an isosceles
triangle.

12. Equilateral Triangle:
An equilateral triangle is
equiangular and an
equiangular triangle is
equilateral.

13. Find the missing angle measures.
mÐa =
mÐb=

14. Find the missing angle measures.
mÐc =
mÐd=

15. Find the missing angle measures.
mÐe =
mÐf =
mÐg =