Download 1.4 Notes

Geometry
Advice from former
students:
“Focus and speak up,
because if you get
confused but don’t say
anything and just keep
moving on, you’ll get
lost”
Today:
 Homework Check
 1.4 Instruction
 Practice
Friday
Advice from former
students:
“Focus and speak up,
because if you get
confused but don’t say
anything and just keep
moving on, you’ll get
lost”
Assignment:
 1.3 p 30 3, 9, 13, 22, 49,
74
1.2/1.3
Check Up
Sketch the figure described.
1. Two rays that intersect at their initial points.
Vocab
2. What is another name for the rays you drew in #1?
3. Two lines intersect at a ________.
___
4. MN represents: ___________________________.
EXAMPLE
ALGEBRA Find the value of n and WX if W is between X
and Y, WX = 6n – 10, XY = 17, and
WY = 3n.
A. n = 3; WX = 8
B. n = 3; WX = 9
C. n = 9; WX = 27
D. n = 9; WX = 44

Content Standards
G.CO.1 Know precise definitions of angle, circle,
perpendicular line, parallel line, and line segment, based on the
undefined notions of point, line, distance along a line, and
distance around a circular arc.
G.CO.12 Make formal geometric constructions with a variety
of tools and methods (compass and straightedge, string,
reflective devices, paper folding, dynamic geometric software,
etc.).
Mathematical Practices
5 Use appropriate tools strategically.
6 Attend to precision.
You measured line segments.
• Measure and classify angles.
• Identify and use congruent angles and the
bisector of an angle.
1.4 Angles and Their Measures
Objectives:
1.Use the Angle Addition Postulate
2.Measure and classify angles
Vocabulary:
angle, vertex, straight angles, adjacent
angles, linear pair, vertical angles
1.4 Angles and Their Measures
What is the picture?
Angle: consists of two different rays that
have the same initial point.
Y
sides
X
vertex
Z
1.4 Angles and Their Measures
Names by vertex or all three letters.
Y
X
vertex
sides
Z
1.4 Angles and Their Measures
When naming angles we must be very
careful, we can use one letter or we may
have to use three letters.
The vertex must always be in the middle of
the name.
We cannot call this
angle B!
B
D
A
List the angles in the
diagram.
C
ABC and CBD
known as linear pair.
1.4 Angles and Their Measures
Angles that have the same measure are called
CONGRUENT angles.
CONGRUENT angles:ÐCBD @ ÐABE
MARK THEM!!!
A
C
Solve for x.
6x + 3
B
2x + 15
Plug in and find angle measures.
D
CBD and ABE
Vertical angles are
are vertical angles.
always congruent.
E
1.4 Angles and Their Measures
BD bisects ABC.
Find x and the
measures of all
angles if
mABD = (2x + 50)o
mDBC = (5x + 5)o
5x + 5 = 2x + 50
-2x
-2x
3x + 5 = 50
3x = 45
x = 15
LABEL!
C
D
A
B
Done?
m ABD = 80°
mDBC = 80°
mCBA = 160°
1.4 Angles and Their Measures
YOUR TURN:
ABC is a right
angle. Find x and
the measures of all
angles if
mABD= 2x + 50 &
mDBC = 5x + 5
C
D
B
A
Review
Given that b bisects segment AB,
AM = x + 5 and MB = 2x – 2, find x.
b
A
M
B
Assignment
Advice from former
students:
Assignment:
“Focus and speak up,
because if you get
confused but don’t say
anything and just keep
moving on, you’ll get
lost”
 Homework Quiz and
 1.4 p 41 #1-4, 9, 37, 39
Vocab Quiz on Thursday