Download angle

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 Angles
Unit 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

 m
TAN
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.