Do Now (Reflection)

Take a protractor from the front of the room.

Take out your compass.

Answer the following questions in your notebook:

How did I feel about the first unit test? (Level of difficulty, level of preparation)

What (if anything) will I do differently to prepare for the second unit test?

What can Ms. Forsyth do to help me better in unit 2?

Intro to AnglesUnit 2

Today’s Objectives

Reflect on Unit 1

Show the measurement of angles and segments on figures

Measure angles using a protractor

Explain congruence of angles

Use problem solving skills

Overall Test Results

Period 1

Period 2

Period 4

Period 5

Period 6

Angle

An angle is formed by two (noncollinear) rays that share a common endpoint.

The common endpoint of the two rays is the vertex of the angle.

The two rays are the sides of the angle.

Naming an angle

By three letters with the vertex in the middle

Or by just the vertex letter ONLY IF it there is only one angle with that vertex.

Can also be named by a number or a variable.

Practice

Name all the angles in this drawing

The measure of an angle

The smallest amount of rotation about the vertex from one ray to the other, measured in degrees.

Can be any value between 0o and 180o.

Reflex measure of an angle

The largest amount of rotation less than 360o.

The measure of an angle and the reflex measure of an angle always add up to 360o.

How to measure an angle

With a protractor!

Step 1: Place the center mark of the protractor on the vertex of the angle you want to measure.

Step 2: Line up the 0-mark with one side of the angle.

Step 3: Read the measure on the protractor scale.

Step 4: Be sure you read the scale that has the 0-mark you are using!

To show the measure of an angle

Use an m before the angle symbol.

For example, m CAB=30o.

Congruent angles

Two angles are congruent if and only if they have equal measure.

Use identical markings to show that two angles in a figure are congruent.

Two types of markings for angles

Angle Bisectors

A ray is an angle bisector if it contains the vertex and divides the angle into two congruent angles.

Name the angle bisector

A

Clock hands

Find the angle formed by the hands of a clock at 2:00

Practice

Name this angle in 3 different ways.

Practice

Draw and label the angles

TAN

m BIG = 35o.

Today’s Objectives

Reflect on Unit 1

Show the measurement of angles and segments on figures

Measure angles using a protractor

Explain congruence of angles

Use problem solving skills

Homework

Complete your “1.2 Poolroom Math” worksheet by tomorrow.

Group Exit Slip!

1. What is the relationship between the measure of an angle and the reflex measure of an angle?

2. Using a protractor, draw a clock face with hands to show 8:00.

3. Measure the angle formed by your clock hands in #2 and use correct notation to write the measure of the angle.

4. Draw a figure that contains at least three angles and includes an angle bisector. Mark any congruent angles.