Download Postulate 3: Protractor Postulate 1.4 Measure and Classify Angles

1.4 Measure and Classify Angles
vocab
angle ­
two rays with the same endpoint
sides ­
rays are the sides of an angle
vertex ­
the endpoint of the rays is called
the vertex of the angle
vertex
sides
Postulate 3: Protractor Postulate
m<AOB = 140o
translation:
The measure of angle AOB, where
A and B are endpoints and O is
the vertex, equals 140 degrees
1
acute angle ­
0o< m<A <90o
right ­
m<A = 90o
obtuse angle­
90o< m<A <180o
straight angle ­
m<A = 180o
K
**Discussion on
naming angles!!**
J
L
N
M
List all of the possible angles above and their angle measures.
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Postulate 4: Angle Addition Postulate
Does this hold true for the angles we just looked at?
?
3
If m<ADC = 72o, then find m<ADB and m<BDC.
(2x
­ 9) o
C
(3
x
+
6) o
B
D
L
(10
x­
(4
x
+
3) o
A
K
N
5) o
M
If m<KNM is a straight angle, then find m<KNL and m<NLM.
If m<ADC is a right angle, then find m<ADB and m<BDC.
o
C
B
(3x
)
­7
(2x ­ 3)o
A
D
4
congruent angles ­
angles that have the same measure
Translations:
5
angle bisector ­
a ray that divides an angle into two congruent angles
X
Y
W
Identify the parts in
the figure above:
vertex ­
sides ­
angle bisector ­
Write a formula for
finding m<XWZ.
Z
Write a formula for
finding m<XWY.
If m<XWZ is 62o and WY is an
angle bisector, find m<YWZ.
If m<XWY is 49o and WY is an
angle bisector, find m<XWZ.
6
homework:
p 28: 3, 5, 6, 7­24 even, 25, 26, 29, 31, 33­38 all, 50, 56 ­ 61 even
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