Download Honors Math 2 Name: Isosceles Triangles Date: Definition of

Honors Math 2
Isosceles Triangles
Name:
Date:
Definition of Isosceles Triangle: A triangle with at least two congruent sides.
Isosceles Triangle Theorem (ITT): If a triangle has two equal sides, then the base angles
(the angles opposite those sides) are congruent.
Given: Isosceles ∆𝐴𝐵𝐶 with base 𝐴𝐶
Prove: ∠𝐴 ≅ ∠𝐶
(Hint: Construct the angle bisector of the vertex angle - ∠𝐵)
Converse of the Isosceles Triangle Theorem (Converse of ITT)
State and prove the converse of the ITT
If ______________________________________________________________________
then ___________________________________________________________________.
Given:
Diagram:
Prove:
Equilateral Triangles: Prove that the angles of an equilateral triangle are equal to 60∘ .
Homework: p. 493-494 #8 p. 497 #3, 5, 8 (Note: Write two-column or paragraph
style proofs. You do not need to write flow chart or reverse list proofs)