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1-4 Angle Measure
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Real-World
+ Vocabulary

Ray- a part of a line

Opposite rays- a point on a line determines exactly 2
rays called opposite rays

Angle- formed by 2 noncollinear rays that have the
same endpoint

Vertex- the common endpoint of the angle

Interior- all points that lie inside the angle

Exterior- all points that lie outside the angle

Degree- unit of angle measurement

Angle Bisector- a ray that divides an angle into 2
congruent angles
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Angle
RAY
INTERIOR
X
110°
EXTERIOR
L
VERTE
X
RAY
P
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Types of Angles
ACUTE ANGLE
-measures less
than 90°
RIGHT ANGLE
-measures 90°
OBTUSE ANGLE
-measures more than 90°
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Examples
Name the vertex of each angle:
1. <4
T
2. <1
W
Name the sides of each angle:
3. <4
ST and UT
4.<STV ST and TV
Write another name for each angle:
5. <3
<WTV
6. <WVT <2
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Practice
Name the vertex of each angle:
1. <5
M
2. <3
P
Name the sides of each angle:
3. <6
NO and NM
4.<MOP
MO and OP
Write another name for each angle:
5. <1
<MPO
6. <QPR <3
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Examples
 Classify
each angle as right, acute, or obtuse:
7. <NMP Right
8.<OMN Acute
9. <QMN
Obtuse
10. If <EBD= 4x+16 & <DBC=6x+4, Find <EBD
4x+16 = 6x+4
4x+16
4(6) +16 = 24+16
12 = 2x
<EBD = 40°
6=x
BISECTOR
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Practice
 Classify
each angle as right, acute, or obtuse:
7. <UZW Right
8.<YZW acute
9. <TZW Obtuse
BISECTOR
10. If <DCE= 4x+15 & <ECF=6x-5, Find <DCE
4x+15 = 6x-5
4x+15
20 = 2x
4(10)+15 = 40 +15
X=10
<DCE = 55°