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Intro ­ Chapter 1.4 Angles.notebook
September 16, 2014
1.4 Measuring Angles
Objective: To find the measures of angles
M.2.B.
Performance Standard 1.6, 3.4, 3.5 DOK­1, 2
Knowledge MA 3
What is an angle???
Angle­ Formed by two rays with the same endpoint.
Vertex­ the endpoint of an angle Sides­ Each ray of the angle
E
How do you NAME angles???
A
Name the following angles:
2
B
1
D
C
F
How do you CLASSIFY angles???
Acute angle­ An angle that measures between 0 and 90 degrees.
Right angle­ An angle that measures 90 degrees.
Obtuse angle­ An angle that measures between 90 and 180 degrees.
Straight angle­ An angle that measures 180 degrees.
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Intro ­ Chapter 1.4 Angles.notebook
September 16, 2014
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Intro ­ Chapter 1.4 Angles.notebook
September 16, 2014
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Intro ­ Chapter 1.4 Angles.notebook
September 16, 2014
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Intro ­ Chapter 1.4 Angles.notebook
September 16, 2014
Postulate 1.7­ Protactor Postulate (similar to ruler postulate)
We can measure angles in terms of real numbers from 0 to 180 degrees.
How do you measure angles???
Practice with handout.
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Intro ­ Chapter 1.4 Angles.notebook
September 16, 2014
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Intro ­ Chapter 1.4 Angles.notebook
September 16, 2014
Postulate 1­8: Angle Addition Postulate­ Adjacent angle measures can be added together to form a large angle measure.
C
A
m < ABC + m < CBD = m < ABD
B
EX 1) m <ZTF = 125
m <UTF = 50 Find m <ZTU
Z
U
T
D
F
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Intro ­ Chapter 1.4 Angles.notebook
EX 2)
September 16, 2014
E
C
D
F
m < CDE= x+4 m<EDF=x+20.
Find x=
m<CDE
m<EDF
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Intro ­ Chapter 1.4 Angles.notebook
September 16, 2014
B
A
m < AOB = 3x + 12
m < BOC = 8x + 34
m < AOD = 6x + 114
Find x.
EX 3)
C
D
O
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Intro ­ Chapter 1.4 Angles.notebook
September 16, 2014
Congruent angles­ Angles that have the exact same measure.
Bisector­ Cuts an angle or a segment into two equal parts.
EX. 4) BX bisects <ABC. If m<ABX = 5x, m<XBC = 3x+10, find x and m<ABC. A
X
B
C
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Intro ­ Chapter 1.4 Angles.notebook
September 16, 2014
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Intro ­ Chapter 1.4 Angles.notebook
September 16, 2014
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Intro ­ Chapter 1.4 Angles.notebook
September 16, 2014
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