DRILL Write the converse of the statement: If today is Monday, then tomorrow is Tuesday. What is the hypothesis and what is the conclusion? If he studies, then he will pass the test.

Geometry Objective Today, we will use and apply properties of isosceles triangles.

Vocabulary What You'll Learn Isosceles Triangles What You'll Learn You will learn to identify and use properties of _______ triangles. isosceles 1) _____________ 2) ____ 3) ____ Vocabulary isosceles triangle base legs

The congruent sides are called ____. legs Isosceles Triangles Recall from §5-1 that an isosceles triangle has at least two congruent sides. The congruent sides are called ____. legs The side opposite the vertex angle is called the ____. base In an isosceles triangle, there are two base angles, the vertices where the base intersects the congruent sides. vertex angle leg base angle base

triangle are congruent, then the angles opposite those sides Isosceles Triangles Theorem 6-2 Isosceles Triangle 6-3 A B C If two sides of a triangle are congruent, then the angles opposite those sides are congruent. The median from the vertex angle of an isosceles triangle lies on the perpendicular bisector of the base and the angle bisector of the vertex angle. A B C

triangle are congruent, then the sides opposite those angles Isosceles Triangles Theorem 6-4 Converse of Isosceles Triangle A B C If two angles of a triangle are congruent, then the sides opposite those angles are congruent. Theorem 6-5 A triangle is equilateral if and only if it is equiangular.

Homework Pages 191 – 192 #’s 1 – 5 #’s 9, 10, 12 – 15 #’s 22 - 26