Name class dateobtuse angle, ∠HLK, is 1608. The measure of the reflex angle, ∠HLK, is 3608 2...
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NAME CLASS DATE 1 © 2015 College Board. All rights reserved. SpringBoard Geometry, Unit 1 Finding the Measure of an Angle You can use a protractor to find the measure of an angle in degrees. Use a protractor to find the measure of each angle. a. C B A b. E F D c. H L K An angle greater than 1808 is called a reflex angle. Solution: a. Position the center of a protractor on the vertex of the angle, ∠B. Align one arm of the angle, such as BC , along the 08 mark. Read the scale where it intersects the other arm, BA . The angle measures 578. 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 C B A 578 b. Position a protractor so ∠E is at its center and ED (or EF ) is at the 08 mark. m∠DEF 5 278. 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 278 E F D c. Use a protractor to find that the measure of the obtuse angle, ∠HLK, is 1608. The measure of the reflex angle, ∠HLK, is 3608 2 1608 5 2008. C 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 1608 H L K EXAMPLE A
Transcript of Name class dateobtuse angle, ∠HLK, is 1608. The measure of the reflex angle, ∠HLK, is 3608 2...
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Name class date
1© 2015 College Board. All rights reserved. SpringBoard Geometry, Unit 1
Finding the Measure of an AngleYou can use a protractor to find the measure of an angle in degrees.
Use a protractor to find the measure of each angle.
a.
CB
A b. E
F
D
c. H L
K
An angle greater than 1808 is called a reflex angle.
Solution:
a. Position the center of a protractor on the vertex of the angle, ∠B. Align one arm of the angle, such as � ��BC , along the 08 mark. Read the scale where it intersects the other arm,
� ��BA . The angle measures 578.
180170
160150
140
130
120110
100908070
60
50
40
3020
100 18017
016
0150140
130 1
20110
100 90 80 70 6050
4030
2010
0
CB
A578
b. Position a protractor so ∠E is at its center and � ���ED (or
� ��EF ) is at the 08 mark. m∠DEF 5 278.
180170
160
150
140
130120
110100
9080
70
60
50
4030
20100
180 170 160 150 140 130 120110
10090
8070
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40
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100
278
E
F
D
c. Use a protractor to find that the measure of the obtuse angle, ∠HLK, is 1608. The measure of the reflex angle, ∠HLK, is 3608 2 1608 5 2008.
C
180
170
160
150
140
130
120110 100 90 80
7060
50
40
3020
100180
170160
150140
1301201101009080706
050
4030
2010
0
1608
H
L
K
ExAMplE A
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2© 2015 College Board. All rights reserved. SpringBoard Geometry, Unit 1
Finding the Measure of an Angle (continued)
Use a protractor to find the measure of ∠CBD in figure ABCD.
A B
CD
Step 1: The sides of ∠CBD are too short to get an accurate result using a protractor. Use a ruler or straightedge to extend the two sides of the angle.
A B
CD
Step 2: Position a protractor so ∠CBD is at its center and BD is at 08. The measure of ∠CBD is 758.
C
180
170
160
150
140
130120 110 100
9080
70
60
5040
3020
100180
170160
150140
13012011010090807060
5040
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2010
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B
C
A
D
758
08
ExAMplE B
pRACTICEUse a protractor to measure each angle.
1. ∠P
P
2. ∠Q
Q
Use the diagram below for Items 3–6. Use a protractor to find the measure of each angle.
3.
4.
5.
6.
∠AYE
∠EYC
∠BYC
∠EYB
Y
B
C
D
E
A
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3© 2015 College Board. All rights reserved. SpringBoard Geometry, Unit 1
Finding the Measure of an Angle (continued)
Use the diagram below for Items 7 and 8. Extend the lengths of the sides and use a protractor to find the measure of each angle.
7.
8.
∠N
∠M
TN
M
