Properties of Isosceles Triangles

Objectives:

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.

Isosceles Triangle Theorem

If a triangle is isosceles, then _______________________.base angles are congruent

Converse of Isosceles Triangle:

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

Equilateral Triangle:

An equilateral triangle is equiangular and an equiangular triangle is equilateral.

Find the missing angle measures.

ma =

mb=

Find the missing angle measures.

mc =

md=

Find the missing angle measures.

me =

mf =

mg =