1. GT Geometry 12/11/12
1. Draw two segments on your paper,
one 7 cm long and the other 9cm long.
2. Construct a triangle with two sides
congruent using the segments you
drew.

2. Objective:
To develop and apply
the Isosceles Triangle
Theorem

3. Do you remember?
What is the definition of
an isosceles triangle?

4. ISOSCELES TRIANGLE
vocabulary
legs Q
vertex angle
base
base angles
Y P

5. Isosceles Triangle Theorem
If two sides of a triangle
are congruent, then the
angles opposite those
sides are congruent.
C
B A

6. ??????????????????????
?
Is the converse true ?

7. Converse Isosceles
Triangle Theorem
If two angles of a
triangle are congruent,
then the sides opposite
those angles are
congruent.

8. ????????
What if I bisect the vertex angle, what can you
tell me?
x
70º

9. ????????
Find base
x –1
2 3x + 3
9 –x

10. ????????
x
70º

11. ????????
Find the missing angles
x
70º

12. Eyes on Isosceles
Triangles