1. Properties of Special Triangles
Objective:
Write conjectures about isosceles triangles

2. Isosceles Triangle
Vertex angle
legs
base
Base angles

3. Construct an Isosceles Triangle Draw an angle, label it C
Mark congruent segments along each side. Label A and B
Connect A and B
Measure and label base angles.
Is there a pattern? A B
Base angles
Isosceles Triangle Conjecture
If a triangle is isosceles, then ________________________
its base angles are congruent.

4. Does this conjecture apply to an equilateral triangle?
All isosceles conjectures apply to equilateral triangles

5. Converse of the Isosceles Triangle Conjecture
Is the converse true?
Converse of the Isosceles Triangle Conjecture
If a triangle has two congruent angles, then ___________________________ C
it is an isosceles triangle.
Draw a segment and label AB
Draw an acute angle at point A
Copy at point B.
Label point of intersection C
Measure AC and BC A B

6. Example Pg 206 #1-7, 10, 11 Find the following: A 7cm E 960 420 3 cm CB D
Find the following: