Lesson 1: 4.1/4.2

Lesson 2: 4.3

Lesson 3: 4.4/4.5

Lesson 4: 4.4/4.5

Lesson 5: 4.7

Lesson 6: 4.6

Lesson 7: 4.8

Lesson 8: Review

Warm Up

USING A RULER, draw a triangle that fills the

space in your notes.

Pass your triangle to a partner.

Measure the angles in the triangle.

What do you notice?

Triangle Sum Conjecture

The sum of the measures of the angles in

every triangle ________________________. equals 180°

In this lesson we will answer…

How are the measures of the angles in a

triangle related?

Using the Triangle Sum Conjecture

Using the Triangle Sum Conjecture

Using the Triangle Sum Conjecture

Angles of a Triangle

Use the Triangle Sum Conjecture and your

algebra skills to solve for x.

Angles of a Triangle

Angles of a Triangle

Angles of a Triangle

Angles of a Triangle

In this lesson we will answer…

Do I remember the parts of an isosceles

triangle?

Is there anything special about the angles of

an isosceles triangle?

What can I assume to be true of any

isosceles triangle?

Parts of the Isosceles Triangle

Using the triangle provided:

Measure AB and BC.

What is true of these sides?

Fold triangle ABC to compare A and C.

What is true of A and C?

Check with your partners!

Vertex Angle

Base

Base Angle Base Angle

Leg Leg

DEF: An isosceles triangle has at least 2 congruent sides

Parts of the Isosceles Triangle

Isosceles Triangle Conjecture

If a triangle is isosceles, then

_______________________________.

Converse of the Isosceles Triangle Conjecture

If a triangle has ____________________

then it is __________________________.

the base angles are congruent

congruent base angles

isosceles

Examples

Examples

Examples

What STUCK with You?

Complete the Ticket Out the Door.

Explain how you arrived at each answer.

Almost Finished…

Clear Your Calculator and Turn It Off

2nd + 7 1 2 then 2nd On

Take out your agenda – copy down due dates

Quizzes

Tests

Homework

Practice 4.1 and 4.2

Do NOT pack up until you are told to do so!