Isos Triangles

5.2 Properties of Isosceles Triangles

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



Isosceles Triangle – at least two sides have the same length



equilateral triangle – isosceles triangle with all three sides are congruent



Parts of Isosceles Triangle:

vertex angle – between two  sides



Parts of Isosceles Triangle:

base angles – angles

opposite  sides



Parts of Isosceles Triangle:

base – side opposite vertex



Name each part of the isosceles triangle below.



Name each part of the isosceles triangle below.



Name each part of the isosceles triangle below.



C-27 Isosceles Triangle Conj. If a triangle is isosceles, then base angles are congruent _______________________.



C-28 Converse of Isosceles Triangle Conjecture:



If a triangle has two congruent angles, it is an isosceles triangle.



C-29 Equilateral Triangle Conj. An equilateral triangle is equiangular and an equiangular triangle is equilateral.



Find the missing angle measures.



ma =

mb=



Find the missing angle measures.



mc =

md=



Find the missing angle measures.



me =

mf = mg =