9. the common
point where
the two rays
meet
vertex
the rays that
make up the
angle
arms
the measure
of the size of
an angle
degrees
10. Naming Angles
1
One way is to use
the ∠symbol followed
by three letters.
The first and third
letters indicate points
on the two arms.
The letter in the middle
is the vertex.
A B C
∠
∠
C B A
11. Naming Angles
using the ∠symbol
only with the vertex
point.
The angle would
be called ∠B.
by using the ∠symbol
followed by the letter
or number between
the angle.
Thiswould be ∠
1.
1
∠ABC
∠CBA
∠CAB
∠BCA
∠B ∠1
18. Measuring Angles
Place the center of the protractor on the vertex B
A
B C
Adjust the 0° baseline of the protractor so that it lines
up with line BC
19. Measuring Angles
B C
Place the center of the protractor on the vertex B
Adjust the 0° baseline of the protractor so that it lines
up with line BC
Since the angle is acute and the 0° line or baseline was used
from the right, you will take the reading from the inner scale
A
30°
32. Let’s work together!
It is the only animal
that have fingerprints.
5 3 2 4 1
A – 20°
D – 60°
E – 35°
G – 110°
K – 155°
L – 120°
N – 160°
O – 145°
P – 25°
33. Let’s work together!
It is the only animal
that have fingerprints.
K O A L A
5 3 2 4 1
A – 20°
D – 60°
E – 35°
G – 110°
K – 155°
L – 120°
N – 160°
O – 145°
P – 25°
38. Practice 4.4
Complete the chart.
Type of angle Measure of angle
Right angle 900
Acute angle Contains less than 900
Obtuse angle Contains more than 900 but
less than 1800
Straight 1800
Reflex angle Contains more than 1800 but
less than 3600
39. Practice 4.4
Name each angle (a) by its vertex and
(b) by three leters.
a. < Y
b. <XYZ or <ZYX
a. < K
b. <JKL or <LKJ
a. < S
b. <RST or <TSR
a. < E
b. <DEF or <FED
40. Practice 4.4
Find the complementary and
supplementary of each angle.
10.
a. Complementary angles= 900
<R= 300
90-30= 600
b. Supplementary angles =1800
180-30= 500
11.
a. Complementary angles= 900
<Y= 120
90-12= 780
b. Supplementary angles =1800
180-12= 1680
41. Practice 4.4
Find the complementary and
supplementary of each angle.
12.
a. Complementary angles= 900
<J= 610
90-61= 290
b. Supplementary angles =1800
180-61= 1190
13.
a. Complementary angles= 900
<M= 450
90-45= 450
b. Supplementary angles =1800
180-45= 1350
42. Practice 4.4
Determine if each pair of angles is
complentary, supplementary or neither.
14.
<Q= 200
<X= 700
Complementary angle
15.
<D= 1200
<X= 400
160
Neither
43. Practice 4.4
Determine if each pair of angles is
complentary, supplementary or neither.
16.
<A= 470
<O= 1330
180
Supplementary angle
17.
<G= 1050
<H= 950
210
Neither
44. Practice 4.4
Determine if each pair of angles is
complentary, supplementary or neither.
18.
<V= 180
<Y= 720
Complementary angle
19.
<B= 980
<L= 820
Supplementary
46. Practice 4.4
23. <1=940
<2= 860
<3=94 0
860
Find the measure for all angles.
24. <1=730
<2= 1070
<3=73 0
1070
25. <1=139 0
<2=41 0
<3=139 0
41 0
47. Practice 4.4
26. 450
Measure each angle tomthe nearest degre using a protractor. Write the numbers
of degrees in the angle
27. 300
28. 1200
31. 1500
29. 800
30. 650
34. 1250
33. 600
32. 900
48. Practice 4.4
35. <ABC=450
<BCA= 450
<CAB=90 0
Measure the angles in this geometry shapes.
36. <ABC=1020
<BCD= 780
<CDA=1020
<DAB=78 0